Disclosed
CVE-2026-8974
Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. 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 was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Exploitation Probability (EPSS)
Low Priority0.04%
The Exploit Prediction Scoring System (EPSS) uses machine learning to estimate the probability that a vulnerability will be exploited in the wild within the next 30 days.
0% (Theoretical)100% (Certainty)
7-Day Exploitation Trend
Vulnerability Timeline
2 eventsMay 19, 2026
Vulnerability Disclosed
Published to component-level vulnerability database.
May 20, 2026
Last Updated
Record updated with new analysis or tags.
Threat Actor Attribution
PREMIUM INTELAssociated Groups:Lazarus Group, APT28
Ransomware Campaigns:LockBit 3.0, BlackCat
IoCs (Indicators):14 IPs, 3 Hashes
Remediation & Mitigation
SOLUTIONOfficial patches and mitigation steps are available for this vulnerability.
# Update Command
apt-get update && apt-get upgrade -y specific-package
# Verify installation
dpkg -l | grep package-name
apt-get update && apt-get upgrade -y specific-package
# Verify installation
dpkg -l | grep package-name
Affected Products
2 Total
mozilla/firefoxAll Versions
mozilla/thunderbirdAll Versions
References
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1784128%2C1883230%2C1983677%2C2022390%2C2023116%2C2023657%2C2024255%2C2024418%2C2024441%2C2024447%2C2024966%2C2025412%2C2025467%2C2025940%2C2025950%2C2025956%2C2026284%2C2027247%2C2027255%2C2027288%2C2027306%2C2027322%2C2027332%2C2027333%2C2028266%2C2028292%2C2028319%2C2028526%2C2028870%2C2028876%2C2028882%2C2029062%2C2029309%2C2029414%2C2029422%2C2029428%2C2029447%2C2029732%2C2029785%2C2029793%2C2029813%2C2029899%2C2031028%2C2031457%2C2032039%2C2033610%2C2033854%2C2034498%2C2034628%2C2034978%2C2035966%2C2036668%2C2036905%2C2036930Mozilla
Broken Link
https://www.mozilla.org/security/advisories/mfsa2026-46/Mozilla
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-48/Mozilla
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-50/Mozilla
Vendor Advisory
Am I Vulnerable?
Check your domain or package.json for CVE-2026-8974 exposure.
Vulnerability Details
CVSS Base Score
8.8/ 10
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published Date
May 19, 2026
Last Modified
May 20, 2026
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