CVE-2021-29988: mozilla firefox Out-of-bounds Read
Vulnerability summary
CVE-2021-29988 is a high (CVSS 8.8) Out-of-bounds Read vulnerability in mozilla firefox. EPSS estimates a 1.38% chance of exploitation in the next 30 days, higher than 71.7% of scored vulnerabilities. 1 public exploit is recorded.
Advisory lineage
Upstream 0 · Downstream 37 · Related 23Timeline
- 17-08-2021PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated8.8HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated8.8HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS trend
Probability
1.38%
Chance of exploitation in the next 30 days
Percentile
72%
Versus all other CVEs
30-day change
0.00 pp
From 1.38% on 20-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 foundExploit Reference (bugzilla.mozilla.org)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Ubuntu6 products
- firefox< 91.0+build2-0ubuntu0.18.04.1 | < 91.0+build2-0ubuntu0.20.04.1
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
- mozjs78All versions (No fix recorded)
Mozilla3 products
- firefox≥ unspecified, < 91 | < 91.0
- firefox_esr≥ unspecified, < 78.13 | < 78.13.0
- thunderbird≥ unspecified, < 78.13 | ≥ unspecified, < 91 | < 78.13.0
Debian2 products
- firefox-esr< 78.13.0esr-1
- thunderbird< 1:78.13.0-1
3 vendors · 11 products
