CVE-2021-29970
A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug could only be triggered when accessibility was enabled.*.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.43%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug could only be triggered when accessibility was enabled.*. This vulnerability affects Thunderbird < 78.12, Firefox ESR < 78.12, and Firefox < 90.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 1.43% probability · 73th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-416, CWE-787
- Affected
- mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 1.4% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1709976Exploit, Issue Tracking, Vendor Advisory
- https://security.gentoo.org/glsa/202202-03Third Party Advisory
- https://security.gentoo.org/glsa/202208-14Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-28/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-29/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-30/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1709976Exploit, Issue Tracking, Vendor Advisory
- https://security.gentoo.org/glsa/202202-03Third Party Advisory
- https://security.gentoo.org/glsa/202208-14Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-28/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-29/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2021-30/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.