CVE-2026-82089 in Wallabag
Summary
by MITRE • 08/28/2026
The wallabag (aka fr.gaulupeau.apps.InThePoche) application through 2.6.0 for Android allows XSS because /api/entries data is loaded into a WebView.
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability identified in the wallabag mobile application, specifically versions up to 2.6.0 for the Android platform, represents a significant security flaw rooted in improper handling of user-controllable input within a web view context. Wallabag is an open-source self-hostable application designed for saving and reading articles later, functioning as a read-it-later service. The core issue arises from how the application processes data retrieved via its API endpoint /api/entries. This endpoint returns content that includes HTML or JavaScript snippets which are subsequently rendered directly within a WebView component without adequate sanitization or encoding. A WebView is an Android view that displays web pages, effectively acting as a lightweight browser embedded within the app. When maliciously crafted payloads are present in the data fetched from this API and injected into the WebView's document object model, they execute with the privileges of the application itself rather than being sandboxed strictly to the website domain.
This architectural oversight leads directly to Cross-Site Scripting, commonly referred to as XSS, within a mobile context. In traditional web applications, XSS allows attackers to inject client-side scripts into webpages viewed by other users. However, in this Android application scenario, the impact is amplified because the executed JavaScript runs with higher privileges than typical browser-based attacks. The attacker can exploit this flaw to access sensitive information stored locally on the device, such as authentication tokens, saved credentials for third-party services linked within articles, or personal data contained within the saved entries. Furthermore, since the WebView has access to Android intents and potentially other application interfaces depending on how it is configured, an attacker could theoretically perform actions on behalf of the user, such as sending messages, accessing contacts if permissions are granted, or redirecting the user to malicious external sites that may attempt further exploitation through social engineering techniques.
From a technical classification perspective, this vulnerability aligns with CWE-79: Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting. More specifically, it falls under the category of Stored XSS if the malicious content is saved in the database and served to other users upon retrieval, or Reflected XSS if the payload is processed immediately during a session without persistent storage. The attack vector leverages ATT&CK technique T1059.007: JavaScript, which describes adversaries using JavaScript for execution within web browsers or embedded views. In mobile environments, this often intersects with data exfiltration techniques where sensitive application state and user credentials are harvested to facilitate further lateral movement or account takeover in associated backend services that share authentication states via cookies or tokens managed by the WebView.
The operational impact of this vulnerability extends beyond simple script execution. It compromises the confidentiality and integrity of the user's saved content and potentially their broader digital identity if single sign-on mechanisms are involved. Users who rely on wallabag to store sensitive professional documents, personal notes containing private information, or credentials for other services face a direct risk of data theft. Additionally, because mobile applications often maintain persistent sessions to avoid frequent re-authentication, the window of opportunity for an attacker to exploit this vulnerability remains open as long as the user keeps the application installed and logged in. This persistence makes the threat particularly severe compared to transient web-based XSS attacks that might be mitigated by clearing browser history or cookies after a short period.
Mitigation strategies must focus on strict input validation and output encoding principles applied at multiple layers of the application stack. The primary defense involves ensuring that any HTML content retrieved from the /api/entries endpoint is sanitized before being injected into the WebView. This can be achieved by using robust sanitization libraries such as OWASP Java Encoder or Android-specific utilities like Jsoup, which strip out dangerous tags and attributes while preserving safe formatting. Alternatively, if rendering rich text is not strictly required for all entries, converting HTML to plain text prior to display would eliminate the attack surface entirely. Developers should also configure the WebView with appropriate security settings, such as disabling JavaScript execution where it is not functionally necessary, although this may impact legitimate interactive features of saved articles. Implementing a Content Security Policy (CSP) within the WebView can further restrict the sources from which scripts are loaded and executed, adding an additional layer of defense against injected payloads.
Beyond immediate code fixes, long-term remediation requires adopting secure coding practices that prioritize input sanitization over trust in API responses. Regular security audits and static application security testing should be integrated into the development lifecycle to detect such injection flaws early. Users affected by this vulnerability are advised to update their applications immediately if a patched version is available from the official distribution channels. If no patch exists, users should consider revoking access tokens associated with wallabag in any linked third-party services and clearing application data to remove potentially cached malicious content until an upgrade can be performed. Maintaining awareness of how mobile web views interact with local storage and system APIs remains critical for developers building applications that handle user-generated or fetched content from external sources.