CVE-2026-8973
CVE-2026-8973 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-119.
Key facts
- Severity: High (CVSS 3.x base score 8.8)
- EPSS exploit prediction: 0% (25th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-30923
- Weakness: CWE-119
- Affected product: Mozilla Firefox
- Published:
- Last modified:
Description
Memory safety bugs present in 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 and Thunderbird 151.
Frequently asked questions
- What is CVE-2026-8973?
- Memory safety bugs present in 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 and Thunderbird 151.
- How severe is CVE-2026-8973?
- CVE-2026-8973 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-8973 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-8973?
- CVE-2026-8973 primarily affects Mozilla Firefox. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2026-8973?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-8973 have an EU (EUVD) identifier?
- Yes. CVE-2026-8973 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30923.
- When was CVE-2026-8973 published?
- CVE-2026-8973 was published on 2026-05-19 and last updated on 2026-06-30.
References
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=1362365%2C1860538%2C1929005%2C1983353%2C1998526%2C2023271%2C2023943%2C2024244%2C2024260%2C2024443%2C2024665%2C2024774%2C2024916%2C2025346%2C2025357%2C2025406%2C2025434%2C2025488%2C2025496%2C2025942%2C2025947%2C2025968%2C2026279%2C2027159%2C2027239%2C2027276%2C2027308%2C2027310%2C2027324%2C2027329%2C2027363%2C2027381%2C2027382%2C2027383%2C2028274%2C2028884%2C2029060%2C2029065%2C2029068%2C2029281%2C2029293%2C2029297%2C2029303%2C2029439%2C2029448%2C2029703%2C2029720%2C2029721%2C2029723%2C2029770%2C2029771%2C2029782%2C2029818%2C2029885%2C2030100%2C2030379%2C2030385%2C2030979%2C2031119%2C2031122%2C2034119%2C2034791%2C2035209%2C2036666%2C2037986
- https://www.mozilla.org/security/advisories/mfsa2026-46/
- https://www.mozilla.org/security/advisories/mfsa2026-50/
- https://access.redhat.com/security/cve/CVE-2026-8973
- https://bugzilla.redhat.com/show_bug.cgi?id=2479864
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8973.json
Affected products (2)
- cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
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