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CVE-2026-0891

Published: Jan 13, 2026

Modified: Apr 13, 2026

PUBLISHED

Description

Memory safety bugs present in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146 and Thunderbird 146. 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 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.

Vendor	Product	Versions
Mozilla	Firefox	unaffected `140.7 - <= 140.` unaffected `147 - <= `
Mozilla	Thunderbird	unaffected `140.7 - <= 140.` unaffected `147 - <= `

References

Memory safety bugs fixed in Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147

https://www.mozilla.org/security/advisories/mfsa2026-01/

https://www.mozilla.org/security/advisories/mfsa2026-03/

https://www.mozilla.org/security/advisories/mfsa2026-04/

https://www.mozilla.org/security/advisories/mfsa2026-05/

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