CVE-2021-29986
CVSS v3
8.1
HIGH
EPSS Score
1.3 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
A suspected race condition when calling getaddrinfo led to memory corruption and a potentially exploitable crash. *Note: This issue only affected Linux operating systems. Other operating systems are unaffected.* This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.
Technical details
- Published
- 2021-08-17
Frequently asked questions
What is CVE-2021-29986?
A suspected race condition when calling getaddrinfo led to memory corruption and a potentially exploitable crash. *Note: This issue only affected Linux operating systems. Other operating systems are unaffected.* This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.
Is CVE-2021-29986 actively exploited?
Active exploitation of CVE-2021-29986 has not been confirmed. Its EPSS score was 1.3% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-29986?
CVE-2021-29986 has a CVSS v3 base score of 8.1 (HIGH severity).
Is CVE-2021-29986 affecting your environment?
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