CVE-2020-26974

8.8 highEPSS 1.5%

High (8.8) in mozilla. EPSS 1.5% chance of exploitation in the next 30 days.

When flex-basis was used on a table wrapper, a StyleGenericFlexBasis object could have been incorrectly cast to the wrong type. This resulted in a heap user-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

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: 1.5% chance of exploitation in the next 30 days; higher than 74% of CVEs (scores of 2026-10-31)
CWE: CWE-787
Published: 2021-01-07
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=1681022
https://www.mozilla.org/security/advisories/mfsa2020-54/
https://www.mozilla.org/security/advisories/mfsa2020-55/
https://www.mozilla.org/security/advisories/mfsa2020-56/
https://bugzilla.mozilla.org/show_bug.cgi?id=1681022

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