# CVE-2026-54412: MQTT-C Heap Out-of-Bounds Read and Integer Underflow in mqtt_unpack_publish_response()

Status: published. Published: 2026-06-14. Updated: 2026-11-05.

LiamBindle MQTT-C versions prior to 1.1.7 contain a heap-based out-of-bounds read and integer underflow in the mqtt_unpack_publish_response() function in src/mqtt.c. A remote unauthenticated attacker controlling an MQTT broker, or capable of injecting MQTT traffic into an unencrypted session, can crash a subscribed MQTT-C client and potentially disclose adjacent heap memory by sending a single crafted PUBLISH packet.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: TuranSec) — https://github.com/LiamBindle/MQTT-C/pull/208
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: TuranSec) — https://github.com/LiamBindle/MQTT-C/releases/tag/v1.1.7

## Affected products and versions

- LiamBindle / MQTT-C: ≥ 0; < 1.1.7 (affected, semver); 1.1.7 (unaffected, semver). Source: CNA: TuranSec

## Severity and prioritization

- CVSS 4.0: 7.8 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/AU:Y/V:D; source: CNA: TuranSec

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H; source: CNA: TuranSec

- CISA KEV: No listing in collected sources

- EPSS: 0.41% as of 2026-11-04; percentile 35.17%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-125, CWE-191

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/LiamBindle/MQTT-C (CNA: TuranSec; product)

- https://github.com/LiamBindle/MQTT-C/blob/v1.1.6/src/mqtt.c#L1334 (CNA: TuranSec; product)

- https://github.com/LiamBindle/MQTT-C/pull/208 (CNA: TuranSec; patch)

- https://github.com/LiamBindle/MQTT-C/releases/tag/v1.1.7 (CNA: TuranSec; release-notes, patch)

- https://cwe.mitre.org/data/definitions/125.html (CNA: TuranSec; technical-description)

- https://cwe.mitre.org/data/definitions/191.html (CNA: TuranSec; technical-description)

## Provenance

- CNA: TuranSec: https://www.cve.org/CVERecord?id=CVE-2026-54412; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-54412; retrieved 2026-11-05; source updated Not reported

Revision: e4e39e2e184be9e6810f5e6e74ca512d7ec7208c2efa9689a6d3eb66bbc0950b

Canonical: https://y2.dev/cve/CVE-2026-54412

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