diff --git a/README.md b/README.md
index 5753a4a1..eb48a6b0 100644
--- a/README.md
+++ b/README.md
@@ -318,7 +318,6 @@ The following tests are not yet implemented and therefore missing:
 - Mandatory Test 6.1.48
 - Mandatory Test 6.1.49
 - Mandatory Test 6.1.50
-- Mandatory Test 6.1.53
 - Mandatory Test 6.1.54
 - Mandatory Test 6.1.55
 
@@ -429,6 +428,7 @@ export const mandatoryTest_6_1_44: DocumentTest
 export const mandatoryTest_6_1_45: DocumentTest
 export const mandatoryTest_6_1_51: DocumentTest
 export const mandatoryTest_6_1_52: DocumentTest
+export const mandatoryTest_6_1_53: DocumentTest
 ```
 
 [(back to top)](#bsi-csaf-validator-lib)
diff --git a/csaf_2_1/mandatoryTests.js b/csaf_2_1/mandatoryTests.js
index c302572e..4edab1cd 100644
--- a/csaf_2_1/mandatoryTests.js
+++ b/csaf_2_1/mandatoryTests.js
@@ -64,3 +64,4 @@ export { mandatoryTest_6_1_44 } from './mandatoryTests/mandatoryTest_6_1_44.js'
 export { mandatoryTest_6_1_45 } from './mandatoryTests/mandatoryTest_6_1_45.js'
 export { mandatoryTest_6_1_51 } from './mandatoryTests/mandatoryTest_6_1_51.js'
 export { mandatoryTest_6_1_52 } from './mandatoryTests/mandatoryTest_6_1_52.js'
+export { mandatoryTest_6_1_53 } from './mandatoryTests/mandatoryTest_6_1_53.js'
diff --git a/csaf_2_1/mandatoryTests/mandatoryTest_6_1_53.js b/csaf_2_1/mandatoryTests/mandatoryTest_6_1_53.js
new file mode 100644
index 00000000..1a32106f
--- /dev/null
+++ b/csaf_2_1/mandatoryTests/mandatoryTest_6_1_53.js
@@ -0,0 +1,79 @@
+import Ajv from 'ajv/dist/jtd.js'
+import { compareZonedDateTimes } from '../dateHelper.js'
+
+const ajv = new Ajv()
+
+/*
+  This is the jtd schema that needs to match the input document so that the
+  test is activated. If this schema doesn't match it normally means that the input
+  document does not validate against the csaf json schema or optional fields that
+  the test checks are not present.
+ */
+const inputSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  properties: {
+    vulnerabilities: {
+      elements: {
+        additionalProperties: true,
+        optionalProperties: {
+          first_known_exploitation_dates: {
+            elements: {
+              additionalProperties: true,
+              optionalProperties: {
+                date: { type: 'string' },
+                exploitation_date: { type: 'string' },
+              },
+            },
+          },
+        },
+      },
+    },
+  },
+})
+
+const validate = ajv.compile(inputSchema)
+
+/**
+ * This implements the mandatory test 6.1.53 of the CSAF 2.1 standard.
+ *
+ * @param {any} doc
+ */
+export function mandatoryTest_6_1_53(doc) {
+  /*
+      The `ctx` variable holds the state that is accumulated during the test ran and is
+      finally returned by the function.
+      */
+  const ctx = {
+    errors:
+      /** @type {Array<{ instancePath: string; message: string }>} */ ([]),
+    isValid: true,
+  }
+
+  if (!validate(doc)) {
+    return ctx
+  }
+
+  doc.vulnerabilities?.forEach((vulnerability, vulnerabilityIndex) => {
+    const exploitationDates = vulnerability.first_known_exploitation_dates || []
+    exploitationDates.forEach((item, Index) => {
+      const date = item.date
+      const exploitationDate = item.exploitation_date
+
+      if (
+        compareZonedDateTimes(
+          /** @type {string} */ (date),
+          /** @type {string} */ (exploitationDate)
+        ) < 0
+      ) {
+        ctx.isValid = false
+        ctx.errors.push({
+          instancePath: `/vulnerabilities/${vulnerabilityIndex}/first_known_exploitation_dates/${Index}`,
+          message:
+            'the "exploitation_date" is newer than the "date" which states when that information was last updated',
+        })
+      }
+    })
+  })
+
+  return ctx
+}
diff --git a/tests/csaf_2_1/mandatoryTest_6_1_53.js b/tests/csaf_2_1/mandatoryTest_6_1_53.js
new file mode 100644
index 00000000..3a2ec48b
--- /dev/null
+++ b/tests/csaf_2_1/mandatoryTest_6_1_53.js
@@ -0,0 +1,46 @@
+import assert from 'node:assert/strict'
+import { mandatoryTest_6_1_53 } from '../../csaf_2_1/mandatoryTests/mandatoryTest_6_1_53.js'
+
+describe('mandatoryTest_6_1_53', function () {
+  it('only runs on relevant documents', function () {
+    assert.equal(mandatoryTest_6_1_53({ document: 'mydoc' }).isValid, true)
+  })
+
+  it('skips empty vulnerability', function () {
+    assert.equal(
+      mandatoryTest_6_1_53({
+        vulnerabilities: [
+          {}, // should be ignored
+          {
+            first_known_exploitation_dates: [
+              {
+                date: '2024-01-24T12:34:56.789Z',
+                exploitation_date: '2024-01-24T13:00:00.000Z',
+              },
+            ],
+          },
+        ],
+      }).isValid,
+      false
+    )
+  })
+
+  it('skips empty first_known_exploitation_date', function () {
+    assert.equal(
+      mandatoryTest_6_1_53({
+        vulnerabilities: [
+          {
+            first_known_exploitation_dates: [
+              {}, // should be ignored
+              {
+                date: '2024-01-24T12:34:56.789Z',
+                exploitation_date: '2024-01-24T13:00:00.000Z',
+              },
+            ],
+          },
+        ],
+      }).isValid,
+      false
+    )
+  })
+})