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8.8
Firefox, Thunderbird: Data Loss from Crashed Web Browsers
CVE-2026-2769
Summary
This issue in Firefox and Thunderbird allows malicious websites to potentially delete important browser data. Users with unpatched versions of these browsers are at risk of losing stored browser data, such as login credentials and saved passwords. Update to the latest version to prevent potential data loss.
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 | <= 115.33.0 | – |
| mozilla | firefox | <= 148.0 | – |
| mozilla | firefox | > 128.0 , <= 140.8.0 | – |
| mozilla | thunderbird | <= 140.8.0 | – |
| mozilla | thunderbird | <= 148.0 | – |
Original title
Use-after-free in the Storage: IndexedDB component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
Original description
Use-after-free in the Storage: IndexedDB component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
nvd CVSS3.1
8.8
Vulnerability type
CWE-416
Use After Free
- https://bugzilla.mozilla.org/show_bug.cgi?id=2014550 Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-13/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-14/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-15/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-16/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-17/ Vendor Advisory
Published: 24 Feb 2026 · Updated: 12 Mar 2026 · First seen: 6 Mar 2026