Readwise Reader Android XSS Persists in Metadata After SVG Patch

Readwise Reader on Android can run script from a poisoned document saved to a user’s reading library. CERT/CC’s September 25 note describes three stored cross-site scripting flaws in version 8.7.2; its confirmed 8.10.1 patch covers the SVG sanitizer flaw. Two official CVE records still list 8.10.1 as affected by metadata-based XSS. For people who import articles, newsletters or shared documents into Reader, the Android app version and the origin of that content both matter now.

The one-minute read: Check the installed Reader version on Android devices that open synchronized documents. Update through Google Play to get the 8.10.1 SVG fix, then treat incoming content from untrusted senders as a live exposure because the header metadata flaw and the URL metadata flaw include 8.10.1 in their affected ranges. Restrict imports from unknown sources and review document titles, author fields and unexpected links before saving or opening them. A newer installed build alone needs a vendor-backed fix statement for those two issues before you mark the exposure resolved.

Poisoned fields reach the WebView

Reader synchronizes saved material between devices. That makes a document imported in one place available to open in the Android app later. CERT/CC credits Zampier Zago of FUNFACTOR1 with reporting the flaws and describes an attacker who can create or modify a document accessible to the user. Opening the poisoned document on Android is the point where its stored content can run in the app’s WebView.

In CVE-2026-18311, document fields such as doc.author and doc.title reach the header without sufficient HTML escaping. The CVE record describes imported author metadata inserted via innerHTML. CVE-2026-18312 is a separate path: URL metadata for an X video fallback or an iOS paywall message is interpolated into an href and inserted into the DOM through innerHTML. Both let crafted metadata become script when the Android view renders it.

The third flaw, CVE-2026-18320, lives in article-body sanitization. A wildcard attribute rule permits all attributes on SVG and PATH elements, including event handlers such as onload and onerror. SVG markup saved in a document can therefore survive sanitization and execute in the WebView. These are three input paths to the same kind of stored XSS, rather than a single vulnerable import field.

One patch covers one path

CERT/CC writes, “As of publication, version 8.10.1 includes a patch that addresses the sanitizer-wildcard issue.” Its CVE record for the SVG flaw marks versions from 8.7.2 up to, but excluding, 8.10.1 as affected. The metadata CVE records mark 8.7.2 through 8.10.1, inclusive, as affected. Check the specific app version before treating a Play Store update as a fix for every route described here.

CERT/CC says successful exploitation could expose stored documents, credentials and session tokens or alter user data within the WebView context. Treat access to those assets as a potential consequence when triaging a suspect document; investigate affected Reader sessions if you find one. CERT/CC says it could not reach Readwise for coordination, and its vendor entry has no statement. A vendor advisory naming a fixed build for both metadata paths would change the patch decision.

Reduce exposure across synced libraries

Start with the Android devices that actually open Reader content. Record each installed version and update through Google Play; 8.10.1 removes the known SVG sanitizer path. Where staff share links, newsletters or imported documents through Reader, pause automatic ingestion of untrusted submissions if you control that workflow. Ask users to review document title, author and destination metadata before saving material from unfamiliar senders, as CERT/CC recommends. Remove suspicious saved items from the library and investigate whether the same document reached other synced Android devices before asking anyone to reopen it.

For verification, compare the installed Android version with the CVE ranges: 8.10.1 is outside the SVG flaw’s range and inside both metadata ranges. Check Reader’s official update information for an explicit fix to CVE-2026-18311 and CVE-2026-18312 before lifting the import restriction. A clean-looking article body is a poor filter for this problem because two of the entry points sit in metadata surrounding the article.