PT-2026-30825 · Mozilla · Firefox+1

Published 2026-04-07 · Updated 2026-04-07 · CVE-2026-5734

Mitre

Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149.0.2 and Firefox ESR < 140.9.1.

Related Identifiers

CVE-2026-5734

Affected Products

Firefox

Firefox Esr

References · 4

• https://mozilla.org/security/advisories/mfsa2026-27 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-25 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-5734 · Security Note
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=2022369%2C2023026%2C2023545%2C2023555%2C2023958%2C2025422%2C2025468%2C2025492%2C2025505 · Note