🛡️ CVE-2025-5269 — firefox

🟠 CVSS 8.1 — High ✅ No Known Exploit CWE-787 NVD

8.1

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128.11 and Thunderbird 128.11.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2025-5269 is classified as CWE-787: Out-of-bounds Write. Data is written past the end or before the start of a buffer, corrupting whatever is stored there.

Affected software

CVE-2025-5269 is recorded against 2 packages.

firefox (fixed in 128.11.0)
thunderbird (fixed in 128.11.0)

Timeline and source

Published on 27 May 2025 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

bugzilla.mozilla.org
www.mozilla.org
www.mozilla.org
lists.debian.org
lists.debian.org

CVE-2025-5269 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Debian Ubuntu

Details

Severity HIGH

CVSS Score 8.1

CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE CWE-787

Public Exploit ✅ No

Source NVD

Published 2025-05-27

Updated 2026-08-11

Modified 2026-06-17

Fix URL N/A

Affected Packages

Software	From version	Fixed in
firefox	—	128.11.0
thunderbird	—	128.11.0

References

Permissions Required https://bugzilla.mozilla.org/show_bug.cgi?id=1924108

Vendor Advisory https://www.mozilla.org/security/advisories/mfsa2025-44/

https://www.mozilla.org/security/advisories/mfsa2025-46/

https://lists.debian.org/debian-lts-announce/2025/05/msg00043.html

https://lists.debian.org/debian-lts-announce/2025/05/msg00046.html

🔗 NVD 🔗 Mitre

Similar Threats

Unknown ALSA-2022:8580
Unknown ALSA-2022:8554
Unknown ALSA-2022:7070
Unknown ALSA-2022:7071
Unknown ALSA-2022:7020

Site Security Check

Is firefox part of your stack?

CVE-2025-5269 is rated CVSS 8.1 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.

Scan My Site Free →

No credit card required · Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.