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8.8
Firefox & Thunderbird: Data Leak from Old Memory
CVE-2026-2798
Summary
Old versions of Firefox and Thunderbird can leak sensitive data due to a bug that allows an attacker to access memory that should have been deleted. This poses a risk to users who visit malicious websites. Update to the latest version to fix this issue.
What to do
No fix is available yet. Check with your software vendor for updates.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| mozilla | firefox | <= 148.0 | – |
| mozilla | thunderbird | <= 148.0 | – |
Original title
Use-after-free in the DOM: Core & HTML component. This vulnerability affects Firefox < 148 and Thunderbird < 148.
Original description
Use-after-free in the DOM: Core & HTML component. This vulnerability affects Firefox < 148 and Thunderbird < 148.
nvd CVSS3.1
8.8
Vulnerability type
CWE-416
Use After Free
- https://bugzilla.mozilla.org/show_bug.cgi?id=2014136 Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-13/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-16/ Vendor Advisory
Published: 24 Feb 2026 · Updated: 12 Mar 2026 · First seen: 6 Mar 2026