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CVE-2021-23992

16
FAUCET Score

CVE-2021-23992 describes a vulnerability in Mozilla Thunderbird versions prior to 78.9.1 where the application failed to validate self-signatures on user IDs associated with OpenPGP keys. This flaw allows an attacker to craft a malicious OpenPGP key with a false user ID, potentially misleading Thunderbird users into believing the false ID is legitimate. The vulnerability has a CVSS score of 4.3 (Medium), indicating a network-based attack requiring user interaction, with a low impact on integrity. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage regarding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 78.9.1CPE match
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.3MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.48%
Probability of exploitation in next 30 days
EPSS Percentile
38.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0048 is in the 41st percentile among its peer group of 26,236 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird-0:78.9.1-1.el7_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: thunderbird-0:78.9.1-1.el8_3
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.1 Extended Update SupportFixed in: thunderbird-0:78.9.1-1.el8_1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.2 Extended Update SupportFixed in: thunderbird-0:78.9.1-1.el8_2
View patch
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2021-23992Moderate

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

Apr 8, 2021

References

bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions RequiredVendor Advisory
mozilla.org / security/advisories/mfsa2021-13
Release NotesVendor Advisory