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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-54521
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 21:17:16 UTC
Updated2026-09-23 18:12:04 UTC
DescriptionFairEmail 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.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from [email protected]

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

EPSS: 0.002360000 probability, percentile 0.148140000 (date 2026-09-23)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.1MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
3.1CNADECLARED6.1MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA M66B FairEmail affected < 1.2319 Not specified

References

ReferenceSourceLinkTags
github.com/M66B/FairEmail/commit/fb37bbfabf5e75d08f0cfa6ce9b84469d62a20a0 [email protected] github.com
github.com/M66B/FairEmail/security/advisories/GHSA-r8ff-qr7g-pvw6 [email protected] github.com
github.com/M66B/FairEmail/releases/tag/1.2319 [email protected] github.com
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