9.8

CVE-2021-43529: mozilla thunderbird Out-of-bounds Write

CVSS: 9.8v3.1CriticalModified
AliasesUBUNTU-CVE-2021-43529DEBIAN-CVE-2021-43529
Published 16-02-2023Last modified 19-03-2025
Open JSON

Vulnerability summary

CVE-2021-43529 is a critical (CVSS 9.8) Out-of-bounds Write vulnerability in mozilla thunderbird. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39.2% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.47%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 6
DLA-2874-1DSA-5034-1RHSA-2021:4130RHSA-2021:4132RHSA-2021:4133RHSA-2021:4134

Timeline

  1. 16-02-2023
    PublishedVulnerability first disclosed.
  2. 19-03-2025
    Last modifiedVulnerability information updated.

Description

Thunderbird versions prior to 91.3.0 are vulnerable to the heap overflow described in CVE-2021-43527 when processing S/MIME messages. Thunderbird versions 91.3.0 and later will not call the vulnerable code when processing S/MIME messages that contain certificates with DER-encoded DSA or RSA-PSS signatures.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.47%

Chance of exploitation in the next 30 days

Percentile

39%

Versus all other CVEs

30-day change

0.00 pp

From 0.47% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.47%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian1 product
  • thunderbird< 1:91.3.0-1
Mozilla1 product
Ubuntu1 product
  • thunderbird< 1:91.5.0+build1-0ubuntu0.18.04.1 | < 1:91.5.0+build1-0ubuntu0.20.04.1

3 vendors · 3 products

References

5 links