PT-2026-27388 · Mozilla · Firefox+2

Sajeeb Lohani · Published 2026-03-24 · Updated 2026-03-24 · CVE-2026-4689

Positive Technologies · (AI Summary)

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 149 Firefox ESR versions prior to 115.34 Firefox ESR versions prior to 140.9 Thunderbird versions prior to 149 Thunderbird versions prior to 140.9

Description A sandbox escape is possible due to incorrect boundary conditions and an integer overflow within the XPCOM component. This issue could allow an attacker to bypass security restrictions.

Recommendations Update Firefox to version 149 or later. Update Firefox ESR to version 115.34 or later. Update Firefox ESR to version 140.9 or later. Update Thunderbird to version 149 or later. Update Thunderbird to version 140.9 or later.

Related Identifiers

CVE-2026-4689

Affected Products

Firefox

Firefox Esr

Thunderbird

References · 7

• https://mozilla.org/security/advisories/mfsa2026-23 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-4689 · Security Note
• https://mozilla.org/security/advisories/mfsa2026-24 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-20 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-22 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-21 · Vendor Advisory
• https://bugzilla.mozilla.org/show_bug.cgi?id=2016374 · Note