isso-comments isso Moderation Edit Endpoint Website cross site scripting

Summaryinfo

A vulnerability was found in isso-comments isso and classified as problematic. The impacted element is an unknown function of the component Moderation Edit Endpoint. Such manipulation of the argument Website leads to cross site scripting. This vulnerability is listed as CVE-2026-27469. The attack may be performed from remote. There is no available exploit. Applying a patch is advised to resolve this issue.

Detailsinfo

A vulnerability was found in isso-comments isso (the affected version is unknown) and classified as problematic. Affected by this issue is an unknown code of the component Moderation Edit Endpoint. The manipulation of the argument website with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes:

Isso is a lightweight commenting server written in Python and JavaScript. In commits before 0afbfe0691ee237963e8fb0b2ee01c9e55ca2144, there is a stored Cross-Site Scripting (XSS) vulnerability affecting the website and author comment fields. The website field was HTML-escaped using quote=False, which left single and double quotes unescaped. Since the frontend inserts the website value directly into a single-quoted href attribute via string concatenation, a single quote in the URL breaks out of the attribute context, allowing injection of arbitrary event handlers (e.g. onmouseover, onclick). The same escaping is missing entirely from the user-facing comment edit endpoint (PUT /id/) and the moderation edit endpoint (POST /id//edit/). This issue has been patched in commit 0afbfe0691ee237963e8fb0b2ee01c9e55ca2144. To workaround, nabling comment moderation (moderation = enabled = true in isso.cfg) prevents unauthenticated users from publishing comments, raising the bar for exploitation, but it does not fully mitigate the issue since a moderator activating a malicious comment would still expose visitors.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-27469 since 02/19/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Applying the patch 0afbfe0691ee237963e8fb0b2ee01c9e55ca2144 is able to eliminate this problem. The bugfix is ready for download at github.com.

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Productinfo

Vendor

• isso-comments

Name

• isso

License

• open-source

Website

• Product: https://github.com/isso-comments/isso/

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