CVE-2026-0818
4.3 · MEDIUMOverview
CVE-2026-0818 is a medium-severity vulnerability affecting mozilla thunderbird. It was published on January 28, 2026 and has a CVSS 3.1 base score of 4.3 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
When a user explicitly requested Thunderbird to decrypt an inline OpenPGP message that was embedded in a text section of an email that was formatted and styled with HTML and CSS, then the decrypted contents were rendered in a context in which the CSS styles from the outer messages were active. If the user had additionally allowed loading of the remote content referenced by the outer email message, and the email was crafted by the sender using a combination of CSS rules and fonts and animations, then it was possible to extract the secret contents of the email. This vulnerability was fixed in Thunderbird 147.0.1 and Thunderbird 140.7.1.
Remediation
Check the references section for vendor advisories and patches from mozilla. Update thunderbird to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| mozilla | thunderbird | >= 0, < 140.7.1 | Affected |
Frequently Asked Questions
What is CVE-2026-0818?
CVE-2026-0818 is a medium-severity vulnerability affecting mozilla thunderbird. It was published on January 28, 2026 and has a CVSS 3.1 base score of 4.3 (MEDIUM).
How severe is CVE-2026-0818?
This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-0818?
Check the references section for vendor advisories and patches from mozilla. Update thunderbird to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-0818?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-0818 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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