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9.8
Firefox and Thunderbird: Integer Overflow in Standard Library Exposes Sensitive Data
CVE-2026-2762
Summary
An integer overflow in the JavaScript Standard Library component of Firefox and Thunderbird could allow attackers to access sensitive information. This means that if you use an affected version of either browser, you may be at risk of data exposure. Update to the latest version to fix the 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 | <= 140.8.0 | – |
| mozilla | firefox | <= 148.0 | – |
| mozilla | thunderbird | <= 140.8.0 | – |
| mozilla | thunderbird | <= 148.0 | – |
Original title
Integer overflow in the JavaScript: Standard Library component. This vulnerability affects Firefox < 148, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
Original description
Integer overflow in the JavaScript: Standard Library component. This vulnerability affects Firefox < 148, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
nvd CVSS3.1
9.8
Vulnerability type
CWE-190
Integer Overflow
- https://bugzilla.mozilla.org/show_bug.cgi?id=2011649 Issue Tracking Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-13/ 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