PT-2026-33971 · Mozilla · Firefox

Published 2026-04-21 · Updated 2026-04-21 · CVE-2026-6785

Mitre

CVSS v3.1

8.1

High

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

Memory safety bugs present in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. 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 was fixed in Firefox 150, Firefox ESR 115.35, and Firefox ESR 140.10.

Fix

Out of bounds Read

Use After Free

Memory Corruption

Weakness Enumeration

CWE-125

CWE-416

CWE-787

Related Identifiers

CVE-2026-6785

Affected Products

Firefox

References · 4

• https://mozilla.org/security/advisories/mfsa2026-31 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-30 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-32 · Vendor Advisory
• https://bugzilla.mozilla.org/buglist.cgi?bug_id=1935995%2C1999158%2C2015952%2C2021909%2C2022026%2C2022041%2C2022088%2C2022276%2C2022335%2C2022338%2C2022373%2C2022597%2C2022874%2C2023276%2C2023544%2C2023551%2C2023599%2C2023608%2C2023814%2C2024233%2C2024239%2C2024241%2C2024242%2C2024250%2C2024251%2C2024343%2C2024422%2C2024425%2C2024440%2C2024442%2C2024446%2C2024458%2C2024463%2C2024478%2C2024650%2C2024653%2C2024654%2C2024655%2C2024656%2C2024661%2C2024662%2C2024668%2C2024919%2C2025278%2C2025349%2C2025350%2C2025354%2C2025360%2C2025363%2C2025370%2C2025379%2C2025381%2C2025399%2C2025400%2C2025403%2C2025407%2C2025415%2C2025420%2C2025427%2C2025429%2C2025430%2C2025479%2C2025489%2C2025493%2C2025497%2C2025502%2C2025515%2C2025517%2C2025526%2C2025609%2C2025948%2C2025949%2C2025951%2C2025953%2C2025955%2C2025962%2C2025969%2C2025970%2C2025971%2C2025973%2C2025976%2C2025977%2C2026280%2C2026285%2C2026293%2C2026296%2C2026310%2C2027237%2C2027260%2C2027268%2C2027277%2C2027284%2C2027291%2C2027293%2C2027298%2C2027330%2C2027342%2C2027345%2C2027359%2C2027365%2C2027378%2C2027754%2C2027959%2C2027962%2C2027964%2C2027971%2C2027974%2C2027979%2C2027982%2C2027995%2C2028001%2C2028267%2C2028268%2C2028275%2C2028288%2C2028290%2C2028291%2C2028528%2C2028551%2C2028627%2C2028879%2C2028889%2C2029061%2C2029071%2C2029283%2C2029296%2C2029314%2C2029323%2C2029411%2C2029423%2C2029424%2C2029425%2C2029427%2C2029436%2C2029440%2C2029449%2C2029450%2C2029458%2C2029462%2C2029468%2C2029472%2C2029690%2C2029707%2C2029708%2C2029728%2C2029802%2C2029896%2C2029906%2C2030106%2C2030118%2C2030123%2C2030135%2C2030230%2C2030320 · Note