CVE-2026-08184.3MediumCWE-200

CVE-2026-0818: CSS-based exfiltration of the content from partially encrypted emails when allowing remote content

Mozilla · Thunderbird

Vendor fix available · Affected: Mozilla Thunderbird · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.2%probability of exploitation in the next 30 days

7th percentile

050100

Higher than 7% of scored CVEs

4.3MediumCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

Mozilla · ThunderbirdVersions not stated

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Information Exposure · Information Disclosure
Vendor: Mozilla
Published: January 2026
Band: Unlikely (under 1%), January 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-0818 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.