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test(security): add poc for LSYN single-byte payload DoS (GHSA-8hqj-422h-c6jx) - #4

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@nbolton nbolton commented Sep 16, 2026

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GHSA-8hqj-422h-c6jx published on 2026-09-10 and the fix is in continuous, so this no longer needs to be embargoed.

To do:

  • Wait for CVE before landing

…22h-c6jx)

Copied across from the embargo repository now the advisory is published. The
fix is in continuous, so this meets the lifecycle rule in the README: advisory
published, fix available.

A one-byte LSYN payload makes setRemoteLayouts bound its loop with
size() - 2, which underflows to SIZE_MAX, so substr() is called past the end
of the view and throws an uncaught std::out_of_range.

Unchanged from the embargo copy.
@nbolton
nbolton force-pushed the poc/ghsa-8hqj-publish branch from cd89c84 to 586906a Compare September 16, 2026 08:35
@nbolton nbolton changed the title Add PoC for LSYN single-byte payload DoS (GHSA-8hqj-422h-c6jx) test(security): add poc for LSYN single-byte payload DoS (GHSA-8hqj-422h-c6jx) Sep 16, 2026
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nbolton commented Sep 16, 2026

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GHSA-8hqj-422h-c6jx - lsyn single-byte payload uncaught exception
malicious server on 127.0.0.1:24800
start a deskflow client (tls disabled) pointed at this address

[*] waiting for client
client connected from 127.0.0.1:45478, helloback: 29 bytes
sent malformed lsyn, payload length 1
[PASS] client survived - odd-length layouts rejected, fix in place

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nbolton marked this pull request as draft September 16, 2026 12:53
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