CVE-2026-8973

HIGH 8.8

Memory safety bugs fixed in Thunderbird 151

CVSS Score

8.8

EPSS Score

0.0%

EPSS Percentile

12th

Memory safety bugs present in Thunderbird 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.

Vendor	mozilla
Product	firefox
Ecosystems	Browser JavaScript
Industries	Technology
Published	May 19, 2026
Last Updated	May 20, 2026

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Affected Versions

Mozilla / Firefox

All versions affected

Mozilla / Thunderbird

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

bugzilla.mozilla.org: 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 mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-46/ mozilla.org: https://www.mozilla.org/security/advisories/mfsa2026-50/

Credits

Andrew Creskey, Andrew Osmond, Dana Keeler, Henri Sivonen, Jed Davis, John Schanck, Jon Coppeard, Justin Link, Michael Froman, Nika Layzell, Noah Lokocz, Randell Jesup, Steve Fink, Tom Schuster and the Mozilla Fuzzing Team