# CVE-2026-103645: Integer overflow vulnerability in QTextCodec fromUnicode() and toUnicode() impacts Qt

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

An integer overflow vulnerability in the Qt QTextCodec fromUnicode() and toUnicode() functionality of the Qt 5 Core Compatibility APIs module (Qt 6) and the Qt Core module (Qt 5). Only builds where Qt is compiled with ICU support are affected.

## 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/qt5compat/+/762795

## Affected products and versions

- qt / qt: ≥ 0; < 5.0.0 (unknown, python); ≥ 5.0.0; < 6.8.9 (affected, python); ≥ 6.9.0; < 6.11.3 (affected, python). Source: CNA: Qt

## Severity and prioritization

- CVSS 4.0: 1.1 (low); CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/R:U/U:Clear; source: CNA: Qt

- CVSS 4.0: 1.1 (low); CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:X/RE:X/U:Clear; source: NVD: a59d8014-47c4-4630-ab43-e1b13cbe58e3

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-190, CWE-835

## Exploit evidence

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

## References

- https://www.qt.io/security-advisories?search=CVE-2026-103645 (CNA: Qt; vendor-advisory)

- https://codereview.qt-project.org/c/qt/qt5compat/+/762795 (CNA: Qt; patch)

- https://codereview.qt-project.org/c/qt/qt5compat/+/762795 (a59d8014-47c4-4630-ab43-e1b13cbe58e3)

- https://www.qt.io/security-advisories?search=CVE-2026-103645 (a59d8014-47c4-4630-ab43-e1b13cbe58e3)

## Provenance

- CNA: Qt: https://www.cve.org/CVERecord?id=CVE-2026-103645; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103645; retrieved 2026-11-13; source updated 2026-11-13

Revision: 87661d5cb841d276e6ec3df04b69dbd4b26aea69d14925d8b8d89afb1b12d80a

Canonical: https://y2.dev/cve/CVE-2026-103645

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