- Description
- 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.
- Source
- security-advisories@github.com
- NVD status
- Deferred
CVSS 3.1
- Type
- Secondary
- Base score
- 6.1
- Impact score
- 2.7
- Exploitability score
- 2.8
- Vector string
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Severity
- MEDIUM
- security-advisories@github.com
- CWE-79
- Hype score
- Not currently trending