Out-of-bounds Read in Mozilla Firefox

CVE-2021-29988

Firefox incorrectly treated an inline list-item element as a block element, resulting in an out of bounds read or memory corruption, and a potentially exploitable crash. This vulnerability affects Thunderbird < 78.13, Thunderbird < 91, Firefox ESR < 78.13, and Firefox < 91.

Vulnerability class: Buffer Overflow

EPSS: 0.014 (69.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-29988?
CVE-2021-29988 is a high-severity vulnerability in Mozilla Firefox, classified under Out-of-bounds Read. CVSS score: 8.8/10. Published 2021-08-17.
How severe is CVE-2021-29988?
High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2021-29988 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.