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

Quick assessment

Affected
M66B FairEmail
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FairEmail 是一款功能齐全、开源且注重隐私保护的 Android 电子邮件应用。在 1.2319 版本之前， 中的 ActivityAMP AMP 消息渲染器在其 WebView 中启用了 JavaScript，但对不可信的消息 HTML 内容未进行充分的净化处理。对于非白名单主机， 仅移除了脚本的 属性，却将内联脚本元素保留在文档中，并且未拒绝其他元素上的事件处理器属性或 URL。 攻击者可构造特殊的 AMP 邮件，当收件人打开该邮件并启用 AMP 开关时，即可执行任意 JavaScript 代码。该恶意

CVSS 6.1 · Medium
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I. Basic Information for CVE-2026-54521

Vulnerability Information
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Vulnerability Title
FairEmail: Cross-site scripting (XSS) in AMP message rendering (ActivityAMP)
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
M66B FairEmail < 1.2319 -

II. Public POCs for CVE-2026-54521

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III. Intelligence Information for CVE-2026-54521

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Patches & Fixes for CVE-2026-54521 (1)

Vendor Advisories for CVE-2026-54521 (1)

Vendor Pages for CVE-2026-54521 (1)

IV. Related Vulnerabilities

Same weakness: CWE-79

V. Comments for CVE-2026-54521

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