PT-2026-27399 · Mozilla · Firefox+2

Pizzahunthack1 · Published 2026-03-24 · Updated 2026-03-24 · CVE-2026-4700

Positive Technologies · (AI Summary)

CVSS v3.1

9.8

Critical

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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

Description A mitigation bypass exists in the Networking: HTTP component. This issue could allow bypassing existing security measures.

Recommendations Update Firefox to version 149 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.

Fix

Related Identifiers

CVE-2026-4700

Affected Products

Firefox

Firefox Esr

Thunderbird

References · 6

• https://mozilla.org/security/advisories/mfsa2026-23 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-4700 · Security Note
• https://mozilla.org/security/advisories/mfsa2026-24 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-22 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-20 · Vendor Advisory
• https://bugzilla.mozilla.org/show_bug.cgi?id=2003766 · Note