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7.5
Firefox, Thunderbird: WebAssembly JavaScript Error Causes Crashes
CVE-2026-2801
Summary
Using Firefox or Thunderbird versions before 148 can cause a crash when encountering certain JavaScript code. This can lead to a denial of service, making the affected application unusable. Update to the latest version (at least 148) 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 | <= 148.0 | – |
| mozilla | thunderbird | <= 148.0 | – |
Original title
Incorrect boundary conditions in the JavaScript: WebAssembly component. This vulnerability affects Firefox < 148 and Thunderbird < 148.
Original description
Incorrect boundary conditions in the JavaScript: WebAssembly component. This vulnerability affects Firefox < 148 and Thunderbird < 148.
nvd CVSS3.1
7.5
Vulnerability type
CWE-754
- https://bugzilla.mozilla.org/show_bug.cgi?id=2009901 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