Is CVE-2026-8974 being actively exploited?

It is not currently in CISA's KEV catalog. Its EPSS exploitation probability is 0%.

What products does CVE-2026-8974 affect?

Tracked products affected include Mozilla Firefox, Mozilla Thunderbird. Check the version you run to see whether it is affected.

How do I fix CVE-2026-8974?

Apply the vendor fix promptly. Upgrade affected products to a fixed version.

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CVE-2026-8974

Q: What is CVE-2026-8974?

CVE-2026-8974 is a high-severity software vulnerability (Memory corruption) with a CVSS score of 8.8. Memory safety bugs present in Firefox ESR 140.10 and Firefox 150. 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 vulnerabili

HIGH severity · CVSS 8.8 · Memory corruption

8.8CVSS HIGH

Summary

Memory safety bugs present in Firefox ESR 140.10 and Firefox 150. 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 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

Impact & exploitability

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionRequired

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Exploit probability (EPSS)0%

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products we track (2)

Mozilla Firefox Mozilla Thunderbird

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Additional information

NVD record
https://www.mozilla.org/security/advisories/mfsa2026-46/Advisory
https://www.mozilla.org/security/advisories/mfsa2026-48/Advisory
https://www.mozilla.org/security/advisories/mfsa2026-50/Advisory
https://www.mozilla.org/security/advisories/mfsa2026-51/Advisory
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1784128%2C1883230%2C1983677%2C2022390%2C2023116%2C2023657%2C2024255%2C2024418%2C2024441%2C2024447%2C2024966%2C2025412%2C2025467%2C2025940%2C2025950%2C2025956%2C2026284%2C2027247%2C2027255%2C2027288%2C2027306%2C2027322%2C2027332%2C2027333%2C2028266%2C2028292%2C2028319%2C2028526%2C2028870%2C2028876%2C2028882%2C2029062%2C2029309%2C2029414%2C2029422%2C2029428%2C2029447%2C2029732%2C2029785%2C2029793%2C2029813%2C2029899%2C2031028%2C2031457%2C2032039%2C2033610%2C2033854%2C2034498%2C2034628%2C2034978%2C2035966%2C2036668%2C2036905%2C2036930