diff --git a/pkg/coordinator/tasks/check_consensus_config_spec/README.md b/pkg/coordinator/tasks/check_consensus_config_spec/README.md
new file mode 100644
index 00000000..2bd510fb
--- /dev/null
+++ b/pkg/coordinator/tasks/check_consensus_config_spec/README.md
@@ -0,0 +1,131 @@
+# Check Consensus Config Spec Task
+
+This task validates that consensus clients properly implement the `/eth/v1/config/spec` endpoint according to the Ethereum consensus specification.
+
+## Description
+
+The task fetches the latest consensus specification from the Ethereum consensus-specs repository, combining the main config with all relevant preset files (phase0, altair, bellatrix, capella, deneb, electra, fulu, etc.), and compares it against the response from each consensus client's `/eth/v1/config/spec` endpoint. It checks for:
+
+1. **Missing required fields** - Fields that should be present according to the spec but are missing from the client response
+2. **Extra fields** - Fields in the client response that are not in the specification (can be allowed or disallowed)
+3. **Value mismatches** - Fields where the client returns a different value than expected
+
+## Configuration
+
+```yaml
+- name: check_consensus_config_spec
+  title: "Validate consensus config spec endpoint"
+  config:
+    clientPattern: ".*"  # Regex pattern to filter clients
+    pollInterval: 10s    # How often to check clients
+    networkPreset: "mainnet"  # Network preset (mainnet or minimal only)
+    specBranch: "dev"    # Git branch to use (dev, master, etc.)
+    presetFiles: []      # Optional: override default preset files
+    requiredFields: []   # If empty, uses all fields from combined spec
+    allowExtraFields: true  # Whether to allow extra fields not in spec
+```
+
+## Parameters
+
+- `clientPattern`: Regex pattern to filter which clients to check (default: ".*" - all clients)
+- `pollInterval`: Interval between checks (default: 10s)
+- `networkPreset`: Network preset to use (default: "mainnet", can be "mainnet" or "minimal" only)
+- `specBranch`: Git branch to use for fetching specs (default: "dev")
+- `presetFiles`: List of preset files to fetch and combine (default: ["phase0.yaml", "altair.yaml", "bellatrix.yaml", "capella.yaml", "deneb.yaml", "electra.yaml", "fulu.yaml"])
+- `requiredFields`: List of fields that must be present (default: empty, uses all fields from combined spec)
+- `allowExtraFields`: Whether to allow fields not in the specification (default: true)
+
+**Note**: The task automatically constructs the correct URLs based on `networkPreset` and `specBranch`:
+- Config: `https://raw.githubusercontent.com/ethereum/consensus-specs/{specBranch}/configs/{networkPreset}.yaml`
+- Presets: 
+  - For `minimal`: `https://raw.githubusercontent.com/ethereum/consensus-specs/{specBranch}/presets/minimal/{presetFile}`
+  - For `mainnet`: `https://raw.githubusercontent.com/ethereum/consensus-specs/{specBranch}/presets/mainnet/{presetFile}`
+
+## Outputs
+
+The task sets the following output variables:
+
+- `validationSummary`: Object containing:
+  - `totalClients`: Total number of clients checked
+  - `validClients`: Number of clients that passed validation
+  - `invalidClients`: Number of clients that failed validation
+  - `results`: Array of validation results for each client
+
+Each result in the `results` array contains:
+- `name`: Client name
+- `isValid`: Whether the client passed validation
+- `missingFields`: Array of required fields that are missing
+- `extraFields`: Array of extra fields (if not allowed)
+- `errorMessage`: Error message if the client couldn't be checked
+- `receivedSpec`: The actual spec returned by the client
+- `comparisonIssues`: Array of value mismatches found
+
+## Example Usage
+
+### Basic usage - check all clients (defaults to mainnet)
+```yaml
+- name: check_consensus_config_spec
+  title: "Validate all clients against mainnet spec"
+  config:
+    clientPattern: ".*"
+```
+
+### Check specific clients only
+```yaml
+- name: check_consensus_config_spec
+  title: "Validate Lighthouse clients only"
+  config:
+    clientPattern: "lighthouse-.*"
+```
+
+### Use minimal preset
+```yaml
+- name: check_consensus_config_spec
+  title: "Validate against minimal preset"
+  config:
+    networkPreset: "minimal"
+```
+
+### Use different network config (holesky example with mainnet presets)
+```yaml
+- name: check_consensus_config_spec
+  title: "Validate against holesky config with mainnet presets"
+  config:
+    # Note: Only mainnet or minimal are valid for networkPreset
+    # For other networks like holesky, they use mainnet presets
+    networkPreset: "mainnet"
+```
+
+### Use master branch instead of dev
+```yaml
+- name: check_consensus_config_spec
+  title: "Validate against master branch specs"
+  config:
+    specBranch: "master"
+```
+
+### Strict validation (no extra fields allowed)
+```yaml
+- name: check_consensus_config_spec
+  title: "Strict spec validation"
+  config:
+    allowExtraFields: false
+```
+
+## Task Behavior
+
+- The task starts by fetching the expected specification from the configured source
+- It then continuously polls all matching clients to check their spec endpoint
+- For each client, it validates the response against the expected specification
+- Results are logged with clear indication of which clients are missing which fields
+- The task succeeds only if all clients pass validation
+
+## Error Handling
+
+The task handles various error scenarios:
+- Network errors when fetching the specification
+- Client timeout or connection errors
+- Invalid response format from clients
+- Missing or malformed data in client responses
+
+All errors are logged with appropriate context and client identification.
\ No newline at end of file
diff --git a/pkg/coordinator/tasks/check_consensus_config_spec/config.go b/pkg/coordinator/tasks/check_consensus_config_spec/config.go
new file mode 100644
index 00000000..80593047
--- /dev/null
+++ b/pkg/coordinator/tasks/check_consensus_config_spec/config.go
@@ -0,0 +1,77 @@
+package checkconsensusconfigspec
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/ethpandaops/assertoor/pkg/coordinator/helper"
+)
+
+type Config struct {
+	// ClientPattern is a regex pattern to filter clients
+	ClientPattern string `yaml:"clientPattern" json:"clientPattern"`
+	// PollInterval is the interval to poll for client updates
+	PollInterval helper.Duration `yaml:"pollInterval" json:"pollInterval"`
+	// NetworkPreset is the network preset to use (mainnet or minimal only)
+	NetworkPreset string `yaml:"networkPreset" json:"networkPreset"`
+	// SpecBranch is the git branch to use for fetching specs (defaults to "dev")
+	SpecBranch string `yaml:"specBranch" json:"specBranch"`
+	// PresetFiles is the list of preset files to fetch and combine (optional override)
+	PresetFiles []string `yaml:"presetFiles" json:"presetFiles"`
+	// RequiredFields specifies which fields are mandatory in the spec response
+	RequiredFields []string `yaml:"requiredFields" json:"requiredFields"`
+	// AllowExtraFields determines if extra fields not in the spec are allowed
+	AllowExtraFields bool `yaml:"allowExtraFields" json:"allowExtraFields"`
+	
+	// Internal computed fields (not configurable by user)
+	specSource    string
+	presetBaseURL string
+}
+
+func DefaultConfig() Config {
+	return Config{
+		ClientPattern:    ".*",
+		PollInterval:     helper.Duration{Duration: 10 * time.Second},
+		NetworkPreset:    "mainnet",
+		SpecBranch:       "dev",
+		PresetFiles:      []string{"phase0.yaml", "altair.yaml", "bellatrix.yaml", "capella.yaml", "deneb.yaml", "electra.yaml", "fulu.yaml"},
+		RequiredFields:   []string{}, // Will be populated from combined spec
+		AllowExtraFields: true,
+	}
+}
+
+func (c *Config) Validate() error {
+	if c.ClientPattern == "" {
+		c.ClientPattern = ".*"
+	}
+	if c.PollInterval.Duration == 0 {
+		c.PollInterval.Duration = 10 * time.Second
+	}
+	if c.NetworkPreset == "" {
+		c.NetworkPreset = "mainnet"
+	}
+	if c.SpecBranch == "" {
+		c.SpecBranch = "dev"
+	}
+	if len(c.PresetFiles) == 0 {
+		c.PresetFiles = []string{"phase0.yaml", "altair.yaml", "bellatrix.yaml", "capella.yaml", "deneb.yaml", "electra.yaml", "fulu.yaml"}
+	}
+	
+	// Validate networkPreset - only mainnet or minimal are valid
+	if c.NetworkPreset != "mainnet" && c.NetworkPreset != "minimal" {
+		return fmt.Errorf("invalid networkPreset '%s': only 'mainnet' or 'minimal' are supported", c.NetworkPreset)
+	}
+	
+	// Compute the URLs based on the network preset and branch
+	c.specSource = fmt.Sprintf("https://raw.githubusercontent.com/ethereum/consensus-specs/%s/configs/%s.yaml", c.SpecBranch, c.NetworkPreset)
+	
+	// For minimal preset, use the correct path
+	if c.NetworkPreset == "minimal" {
+		c.presetBaseURL = fmt.Sprintf("https://raw.githubusercontent.com/ethereum/consensus-specs/%s/presets/minimal", c.SpecBranch)
+	} else {
+		// For mainnet, use the standard mainnet presets
+		c.presetBaseURL = fmt.Sprintf("https://raw.githubusercontent.com/ethereum/consensus-specs/%s/presets/mainnet", c.SpecBranch)
+	}
+	
+	return nil
+}
\ No newline at end of file
diff --git a/pkg/coordinator/tasks/check_consensus_config_spec/task.go b/pkg/coordinator/tasks/check_consensus_config_spec/task.go
new file mode 100644
index 00000000..cc985933
--- /dev/null
+++ b/pkg/coordinator/tasks/check_consensus_config_spec/task.go
@@ -0,0 +1,343 @@
+package checkconsensusconfigspec
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"reflect"
+	"strings"
+	"time"
+
+	"github.com/ethpandaops/assertoor/pkg/coordinator/clients"
+	"github.com/ethpandaops/assertoor/pkg/coordinator/types"
+	"github.com/ethpandaops/assertoor/pkg/coordinator/vars"
+	"github.com/sirupsen/logrus"
+	"gopkg.in/yaml.v2"
+)
+
+var (
+	TaskName       = "check_consensus_config_spec"
+	TaskDescriptor = &types.TaskDescriptor{
+		Name:        TaskName,
+		Description: "Checks consensus clients for compliance with the /eth/v1/config/spec endpoint specification.",
+		Config:      DefaultConfig(),
+		NewTask:     NewTask,
+	}
+)
+
+type Task struct {
+	ctx              *types.TaskContext
+	options          *types.TaskOptions
+	config           Config
+	logger           logrus.FieldLogger
+	expectedSpec     map[string]interface{}
+	expectedSpecKeys []string
+}
+
+type ClientValidationResult struct {
+	Name            string            `json:"name"`
+	IsValid         bool              `json:"isValid"`
+	MissingFields   []string          `json:"missingFields"`
+	ExtraFields     []string          `json:"extraFields"`
+	ErrorMessage    string            `json:"errorMessage"`
+	ReceivedSpec    map[string]interface{} `json:"receivedSpec"`
+	ComparisonIssues []string         `json:"comparisonIssues"`
+}
+
+type ValidationSummary struct {
+	TotalClients   int                      `json:"totalClients"`
+	ValidClients   int                      `json:"validClients"`
+	InvalidClients int                      `json:"invalidClients"`
+	Results        []*ClientValidationResult `json:"results"`
+}
+
+func NewTask(ctx *types.TaskContext, options *types.TaskOptions) (types.Task, error) {
+	return &Task{
+		ctx:     ctx,
+		options: options,
+		logger:  ctx.Logger.GetLogger(),
+	}, nil
+}
+
+func (t *Task) Config() interface{} {
+	return t.config
+}
+
+func (t *Task) Timeout() time.Duration {
+	return t.options.Timeout.Duration
+}
+
+func (t *Task) LoadConfig() error {
+	config := DefaultConfig()
+
+	// parse static config
+	if t.options.Config != nil {
+		if err := t.options.Config.Unmarshal(&config); err != nil {
+			return fmt.Errorf("error parsing task config for %v: %w", TaskName, err)
+		}
+	}
+
+	// load dynamic vars
+	err := t.ctx.Vars.ConsumeVars(&config, t.options.ConfigVars)
+	if err != nil {
+		return err
+	}
+
+	// validate config
+	if err := config.Validate(); err != nil {
+		return err
+	}
+
+	t.config = config
+
+	return nil
+}
+
+func (t *Task) Execute(ctx context.Context) error {
+	// Fetch expected spec from the source
+	if err := t.fetchExpectedSpec(ctx); err != nil {
+		return fmt.Errorf("failed to fetch expected spec: %w", err)
+	}
+
+	t.logger.Infof("Loaded combined spec with %d fields from main config and %d preset files", 
+		len(t.expectedSpecKeys), len(t.config.PresetFiles))
+
+	// Initial check
+	t.processCheck(ctx)
+
+	// Poll for updates
+	for {
+		select {
+		case <-time.After(t.config.PollInterval.Duration):
+			t.processCheck(ctx)
+		case <-ctx.Done():
+			return nil
+		}
+	}
+}
+
+func (t *Task) fetchExpectedSpec(ctx context.Context) error {
+	// Initialize the combined spec
+	t.expectedSpec = make(map[string]interface{})
+
+	// First, fetch the main config spec
+	if err := t.fetchConfigFile(ctx, t.config.specSource); err != nil {
+		return fmt.Errorf("failed to fetch main config spec: %w", err)
+	}
+
+	// Then fetch and combine all preset files
+	for _, presetFile := range t.config.PresetFiles {
+		presetURL := fmt.Sprintf("%s/%s", t.config.presetBaseURL, presetFile)
+		if err := t.fetchConfigFile(ctx, presetURL); err != nil {
+			// Log warning but continue if preset file is not found (some might be optional)
+			t.logger.Warnf("Failed to fetch preset file %s: %v", presetFile, err)
+			continue
+		}
+	}
+
+	// Build the keys list from the combined spec
+	t.expectedSpecKeys = make([]string, 0, len(t.expectedSpec))
+	for key := range t.expectedSpec {
+		t.expectedSpecKeys = append(t.expectedSpecKeys, key)
+	}
+
+	// If no required fields specified in config, use all fields from combined spec
+	if len(t.config.RequiredFields) == 0 {
+		t.config.RequiredFields = t.expectedSpecKeys
+	}
+
+	t.logger.Infof("Combined spec contains %d total fields from main config and %d preset files", 
+		len(t.expectedSpecKeys), len(t.config.PresetFiles))
+
+	return nil
+}
+
+func (t *Task) fetchConfigFile(ctx context.Context, url string) error {
+	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	if err != nil {
+		return fmt.Errorf("failed to create request for %s: %w", url, err)
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("failed to fetch %s: %w", url, err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("failed to fetch %s, status code: %d", url, resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response body from %s: %w", url, err)
+	}
+
+	var config map[string]interface{}
+	if err := yaml.Unmarshal(body, &config); err != nil {
+		return fmt.Errorf("failed to parse YAML from %s: %w", url, err)
+	}
+
+	// Merge the config into the expected spec
+	for key, value := range config {
+		if existingValue, exists := t.expectedSpec[key]; exists {
+			t.logger.Debugf("Overriding spec field %s: %v -> %v", key, existingValue, value)
+		}
+		t.expectedSpec[key] = value
+	}
+
+	return nil
+}
+
+func (t *Task) processCheck(ctx context.Context) {
+	allResultsPass := true
+	validationSummary := &ValidationSummary{
+		Results: []*ClientValidationResult{},
+	}
+
+	clients := t.ctx.Scheduler.GetServices().ClientPool().GetClientsByNamePatterns(t.config.ClientPattern, "")
+	validationSummary.TotalClients = len(clients)
+
+	for _, client := range clients {
+		result := t.validateClient(ctx, client)
+		validationSummary.Results = append(validationSummary.Results, result)
+
+		if result.IsValid {
+			validationSummary.ValidClients++
+		} else {
+			validationSummary.InvalidClients++
+			allResultsPass = false
+		}
+	}
+
+	t.logValidationResults(validationSummary)
+
+	// Set output variables
+	if validationData, err := vars.GeneralizeData(validationSummary); err == nil {
+		t.ctx.Outputs.SetVar("validationSummary", validationData)
+	} else {
+		t.logger.Warnf("Failed setting `validationSummary` output: %v", err)
+	}
+
+	if allResultsPass {
+		t.ctx.SetResult(types.TaskResultSuccess)
+	} else {
+		t.ctx.SetResult(types.TaskResultNone)
+	}
+}
+
+func (t *Task) validateClient(ctx context.Context, client *clients.PoolClient) *ClientValidationResult {
+	result := &ClientValidationResult{
+		Name:            client.Config.Name,
+		MissingFields:   []string{},
+		ExtraFields:     []string{},
+		ComparisonIssues: []string{},
+	}
+
+	checkLogger := t.logger.WithField("client", client.Config.Name)
+
+	// Fetch spec from client
+	receivedSpec, err := client.ConsensusClient.GetRPCClient().GetConfigSpecs(ctx)
+	if err != nil {
+		checkLogger.Errorf("Failed to fetch config specs: %v", err)
+		result.ErrorMessage = fmt.Sprintf("Failed to fetch config specs: %v", err)
+		return result
+	}
+
+	if receivedSpec == nil {
+		checkLogger.Error("Received nil config specs response")
+		result.ErrorMessage = "Received nil config specs response"
+		return result
+	}
+
+	result.ReceivedSpec = receivedSpec
+
+	// Check for missing required fields
+	for _, requiredField := range t.config.RequiredFields {
+		if _, exists := receivedSpec[requiredField]; !exists {
+			result.MissingFields = append(result.MissingFields, requiredField)
+		}
+	}
+
+	// Check for extra fields if not allowed
+	if !t.config.AllowExtraFields {
+		expectedFieldsMap := make(map[string]bool)
+		for _, field := range t.expectedSpecKeys {
+			expectedFieldsMap[field] = true
+		}
+
+		for receivedField := range receivedSpec {
+			if !expectedFieldsMap[receivedField] {
+				result.ExtraFields = append(result.ExtraFields, receivedField)
+			}
+		}
+	}
+
+	// Compare field values with expected spec
+	for field, expectedValue := range t.expectedSpec {
+		if receivedValue, exists := receivedSpec[field]; exists {
+			if !t.compareValues(expectedValue, receivedValue) {
+				result.ComparisonIssues = append(result.ComparisonIssues, 
+					fmt.Sprintf("Field '%s': expected %v (type: %T), got %v (type: %T)", 
+						field, expectedValue, expectedValue, receivedValue, receivedValue))
+			}
+		}
+	}
+
+	result.IsValid = len(result.MissingFields) == 0 && 
+		(t.config.AllowExtraFields || len(result.ExtraFields) == 0) &&
+		len(result.ComparisonIssues) == 0
+
+	return result
+}
+
+func (t *Task) compareValues(expected, received interface{}) bool {
+	// Convert both values to strings for comparison to handle type differences
+	expectedStr := fmt.Sprintf("%v", expected)
+	receivedStr := fmt.Sprintf("%v", received)
+	
+	// Try to compare as strings first
+	if expectedStr == receivedStr {
+		return true
+	}
+	
+	// For numeric values, try to compare with type conversion
+	if reflect.TypeOf(expected).Kind() == reflect.TypeOf(received).Kind() {
+		return reflect.DeepEqual(expected, received)
+	}
+	
+	return false
+}
+
+func (t *Task) logValidationResults(summary *ValidationSummary) {
+	if summary.InvalidClients == 0 {
+		t.logger.Infof("✅ All %d clients passed spec validation", summary.TotalClients)
+		return
+	}
+
+	t.logger.Errorf("❌ %d/%d clients failed spec validation", summary.InvalidClients, summary.TotalClients)
+
+	for _, result := range summary.Results {
+		if !result.IsValid {
+			clientLogger := t.logger.WithField("client", result.Name)
+			
+			if result.ErrorMessage != "" {
+				clientLogger.Errorf("Error: %s", result.ErrorMessage)
+				continue
+			}
+
+			if len(result.MissingFields) > 0 {
+				clientLogger.Errorf("Missing required fields: %s", strings.Join(result.MissingFields, ", "))
+			}
+
+			if len(result.ExtraFields) > 0 {
+				clientLogger.Warnf("Extra fields not in spec: %s", strings.Join(result.ExtraFields, ", "))
+			}
+
+			if len(result.ComparisonIssues) > 0 {
+				clientLogger.Errorf("Value mismatches: %s", strings.Join(result.ComparisonIssues, "; "))
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/pkg/coordinator/tasks/tasks.go b/pkg/coordinator/tasks/tasks.go
index bd482f49..2e4e769f 100644
--- a/pkg/coordinator/tasks/tasks.go
+++ b/pkg/coordinator/tasks/tasks.go
@@ -6,6 +6,7 @@ import (
 	checkclientsarehealthy "github.com/ethpandaops/assertoor/pkg/coordinator/tasks/check_clients_are_healthy"
 	checkconsensusattestationstats "github.com/ethpandaops/assertoor/pkg/coordinator/tasks/check_consensus_attestation_stats"
 	checkconsensusblockproposals "github.com/ethpandaops/assertoor/pkg/coordinator/tasks/check_consensus_block_proposals"
+	checkconsensusconfigspec "github.com/ethpandaops/assertoor/pkg/coordinator/tasks/check_consensus_config_spec"
 	checkconsensusfinality "github.com/ethpandaops/assertoor/pkg/coordinator/tasks/check_consensus_finality"
 	checkconsensusforks "github.com/ethpandaops/assertoor/pkg/coordinator/tasks/check_consensus_forks"
 	checkconsensusproposerduty "github.com/ethpandaops/assertoor/pkg/coordinator/tasks/check_consensus_proposer_duty"
@@ -45,6 +46,7 @@ var AvailableTaskDescriptors = []*types.TaskDescriptor{
 	checkclientsarehealthy.TaskDescriptor,
 	checkconsensusattestationstats.TaskDescriptor,
 	checkconsensusblockproposals.TaskDescriptor,
+	checkconsensusconfigspec.TaskDescriptor,
 	checkconsensusfinality.TaskDescriptor,
 	checkconsensusforks.TaskDescriptor,
 	checkconsensusproposerduty.TaskDescriptor,