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Fencer Intel
medium 4.3

CVE-2021-23992 json

Thunderbird did not check if the user ID associated with an OpenPGP key has a valid self signature.

published 5y ago modified 4mo ago also EUVD-2021-10912

cvss
4.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

Thunderbird did not check if the user ID associated with an OpenPGP key has a valid self signature. An attacker may create a crafted version of an OpenPGP key, by either replacing the original user ID, or by adding another user ID. If Thunderbird imports and accepts the crafted key, the Thunderbird user may falsely conclude that the false user ID belongs to the correspondent. This vulnerability affects Thunderbird < 78.9.1.

Patch / fix

  • Mozilla Thunderbird 78.9.1
  • thunderbird Debian 14, Debian 13, Debian 12 1:78.10.0-1

debian advisories DEBIAN-CVE-2021-23992

  • thunderbird Ubuntu 18.04 LTS 1:78.11.0+build1-0ubuntu0.18.04.2
  • thunderbird Ubuntu 20.04 LTS 1:78.11.0+build1-0ubuntu0.20.04.2

ubuntu advisories UBUNTU-CVE-2021-23992

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • thunderbird RHEL 8 78.9.1-1.el8_3
  • thunderbird RHEL 7 78.9.1-1.el7_9
  • thunderbird RHEL 8.2 EUS 78.9.1-1.el8_2
  • thunderbird RHEL 8.1 EUS 78.9.1-1.el8_1

red hat advisories RHSA-2021:1201RHSA-2021:1193RHSA-2021:1192RHSA-2021:1190

  • MozillaThunderbird SLE Workstation Extension 15 SP2 78.9.1-8.20.1

suse advisories SUSE-SU-2021:1167-1

  • MozillaThunderbird openSUSE Leap 15.2 78.9.1-lp152.2.38.1

opensuse advisories openSUSE-SU-2021:0580-1

  • thunderbird Arch Linux 78.9.1-1

arch linux advisories AVG-1790

Is CVE-2021-23992 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-23992 updated cvss 4.3

Mozilla: A crafted OpenPGP key with an invalid user ID could be used to confuse the user

  • Red Hat Enterprise Linux 6 thunderbird
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) thunderbird 78.9.1-1.el8_3
    fixed: vendor fix RHSA-2021:1193
  • Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird 78.9.1-1.el8_1
    fixed: vendor fix RHSA-2021:1190
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird 78.9.1-1.el8_2
    fixed: vendor fix RHSA-2021:1201
  • Red Hat Enterprise Linux Client (v. 7) thunderbird 78.9.1-1.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) thunderbird 78.9.1-1.el7_9 Red Hat Enterprise Linux Workstation (v. 7) thunderbird 78.9.1-1.el7_9
    fixed: vendor fix RHSA-2021:1192

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • Mozilla Thunderbird

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.