CVE-2020-26959

8.8 highEPSS 1.3%

High (8.8) in mozilla. EPSS 1.3% chance of exploitation in the next 30 days.

During browser shutdown, reference decrementing could have occured on a previously freed object, resulting in a use-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Severity

CVSS 3.1

8.8 high

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

EPSS: 1.3% chance of exploitation in the next 30 days; higher than 70% of CVEs (scores of 2026-10-31)
CWE: CWE-416
Published: 2020-12-09
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox
mozilla:firefox_esr
mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1669466
https://www.mozilla.org/security/advisories/mfsa2020-50/
https://www.mozilla.org/security/advisories/mfsa2020-51/
https://www.mozilla.org/security/advisories/mfsa2020-52/
https://bugzilla.mozilla.org/show_bug.cgi?id=1669466

Check your stack JSON