CVE-2021-43534: debian debian_linux Out-of-bounds Write
Vulnerability summary
CVE-2021-43534 is a high (CVSS 8.8) Out-of-bounds Write vulnerability in debian debian_linux. EPSS estimates a 1.25% chance of exploitation in the next 30 days, higher than 68.9% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 15 · Related 1Timeline
- 08-12-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
Mozilla developers and community members reported memory safety bugs present in Firefox 93 and Firefox ESR 91.2. 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 affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.
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
1.25%
Chance of exploitation in the next 30 days
Percentile
69%
Versus all other CVEs
30-day change
+0.04 pp
From 1.21% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Debian3 products
- firefox-esr< 91.3.0esr-1
- thunderbird< 1:91.3.0-1
- debian_linuxEOL9.0 | 10.0 | 11.0
Mozilla3 products
- firefox≥ unspecified, < 94 | < 94.0
- firefox_esr≥ unspecified, < 91.3 | < 91.3.0
- thunderbird≥ unspecified, < 91.3 | < 91.3.0
Ubuntu1 product
- thunderbird< 1:91.5.0+build1-0ubuntu0.18.04.1 | < 1:91.5.0+build1-0ubuntu0.20.04.1
3 vendors · 7 products
References
15 links- bugzilla.mozilla.org/buglist.cgi?bug_id=1606864%2C1712671%2C1730048%2C1735152X Refsource MISCREPORTBroken LinkIssue TrackingVendor Advisory
- lists.debian.org/debian-lts-announce/2021/12/msg00030.htmlMailing ListX Refsource MLISTThird Party Advisory
- www.debian.org/security/2022/dsa-5034Vendor AdvisoryX Refsource DEBIANIssue TrackingThird Party Advisory
- lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing ListX Refsource MLISTThird Party Advisory