Medium 6.1Published Sep 17, 2026

CVE-2026-54521FairEmail: Cross-site scripting (XSS) in AMP message rendering (ActivityAMP)

Updated under an hour ago (2026-10-19 06:25 UTC)

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It affects M66B FairEmail. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for M66B FairEmail

Exploited in the last 30 days

FairEmail is a fully featured, open source, privacy-friendly email app for Android. Prior to 1.2319, the ActivityAMP AMP message renderer in app/src/main/java/eu/faircode/email/ActivityAMP.java enables JavaScript in its WebView but incompletely sanitizes untrusted message HTML. For non-allowlisted hosts, script.removeAttr("src") leaves inline script elements in the document and does not reject event-handler attributes or javascript: URLs on other elements. A crafted AMP email can execute arbitrary JavaScript when a recipient opens the message and enables the AMP toggle. The script can read the message DOM, exfiltrate message data, and display phishing overlays within the message-body area. Exploitation requires the recipient to enable the AMP toggle, and practical exposure is reduced because AMP email is uncommon. This issue is fixed in version 1.2319.

CVSS: 6.1 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness (CWE): CWE-79
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Sep 18, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

M66B FairEmail m66b:fairemail (from the name)	before 1.2319	CNA record

References

https://github.com/M66B/FairEmail/security/advisories/GHSA-r8ff-qr7g-pvw6x-refsource-confirm
https://github.com/M66B/FairEmail/commit/fb37bbfabf5e75d08f0cfa6ce9b84469d62a20a0x-refsource-misc
https://github.com/M66B/FairEmail/releases/tag/1.2319x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.