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7.5
Firefox and Thunderbird Settings UI allows unauthorized access to sensitive data
CVE-2026-2803
Summary
Older versions of Firefox and Thunderbird have a security flaw in their Settings UI. This means that an attacker could potentially access sensitive information without permission. To protect yourself, update to the latest version of Firefox or Thunderbird.
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
Information disclosure, mitigation bypass in the Settings UI component. This vulnerability affects Firefox < 148 and Thunderbird < 148.
Original description
Information disclosure, mitigation bypass in the Settings UI component. This vulnerability affects Firefox < 148 and Thunderbird < 148.
nvd CVSS3.1
7.5
Vulnerability type
CWE-200
Information Exposure
CWE-693
Protection Mechanism Failure
- https://bugzilla.mozilla.org/show_bug.cgi?id=2012012 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