# CVE-2026-124889

Use-after-free in Firefox/Thunderbird CSS parsing enabling remote code execution.

- Page: https://www.vulneraibility.com/cve/CVE-2026-124889
- CVSS: 8.8
- Known exploited: not in CISA KEV as of our last sync
- EPSS: 0.38% (percentile 32.4)
- CISA SSVC: exploitation none, automatable no, technical impact total (assessed 2026-11-10)
- Weakness: CWE-416
- Published: 2026-11-10

## Affected

- Mozilla Firefox (<160)
- Firefox ESR (<153.7)
- Mozilla Thunderbird (<160)
- Thunderbird ESR (<153.7)

## Impact

Remote code execution via crafted CSS in web content, enabling arbitrary code execution or sandbox escape on affected clients.

## Action

Immediate action required

## Recommendation

Update Firefox/Thunderbird to versions >=160 or ESR 153.7 immediately.

## References

- [other] https://bugzilla.mozilla.org/show_bug.cgi?id=2082033
- [other] https://www.mozilla.org/security/advisories/mfsa2026-125/
- [other] https://www.mozilla.org/security/advisories/mfsa2026-127/
- [other] https://www.mozilla.org/security/advisories/mfsa2026-128/
- [other] https://www.mozilla.org/security/advisories/mfsa2026-129/

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.