# CVE-2026-103653: Out-of-bounds read vulnerability in CoAP message parsing impacts Qt CoAP

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

An out-of-bounds read vulnerability in the Qt CoAP message parsing (QCoapInternalReply::createFromFrame()) of the Qt CoAP module. Processing a malformed CoAP message can cause an application using Qt CoAP to crash (loss of availability) or to continue operating on incorrect data (potential loss of integrity).

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: Qt) — https://codereview.qt-project.org/c/qt/qtcoap/+/760652
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: Qt) — https://codereview.qt-project.org/c/qt/qtcoap/+/761120

## Affected products and versions

- qt / Qt: ≥ 5.13.0; ≤ 6.8.8 (affected, python); ≥ 6.9.0; ≤ 6.11.2 (affected, python); ≥ 0; < 5.13.0 (unaffected, python). Source: CNA: Qt

## Severity and prioritization

- CVSS 4.0: 6.7 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:U/AU:Y/R:U/RE:L/U:Amber; source: CNA: Qt

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-125

## Exploit evidence

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

## References

- https://wiki.qt.io/List_of_known_vulnerabilities_in_Qt_products#CVE-2026-103653: (CNA: Qt; vendor-advisory)

- https://codereview.qt-project.org/c/qt/qtcoap/+/760652 (CNA: Qt; patch)

- https://codereview.qt-project.org/c/qt/qtcoap/+/761120 (CNA: Qt; patch)

## Provenance

- CNA: Qt: https://www.cve.org/CVERecord?id=CVE-2026-103653; retrieved 2026-11-03; source updated 2026-11-03

Revision: 96f80741d7f274e389ce8af68c3e5bdc02a858fcd08006bf44e1da4794ecc2a8

Canonical: https://y2.dev/cve/CVE-2026-103653

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