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CVE-2026-27469— Isso: Stored XSS via comment website field

Quick assessment

Affected
isso-comments isso
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.

Isso是Isso Comments开源的一个评论服务器。 Isso存在安全漏洞，该漏洞源于对网站和作者评论字段的清理和转义不足，可能导致存储型跨站脚本攻击。

CVSS 6.1 · Medium EPSS 0.22% · P12
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I. Basic Information for CVE-2026-27469

Vulnerability Information
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Vulnerability Title
Isso: Stored XSS via comment website field
Source: CVE Program / CVE List V5
Vulnerability 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: 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
Vulnerability Title
Isso 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Isso是Isso Comments开源的一个评论服务器。 Isso存在安全漏洞，该漏洞源于对网站和作者评论字段的清理和转义不足，可能导致存储型跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
isso-comments isso < 0afbfe0691ee237963e8fb0b2ee01c9e55ca2144 -

II. Public POCs for CVE-2026-27469

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III. Intelligence Information for CVE-2026-27469

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Patches & Fixes for CVE-2026-27469 (1)

Vendor Advisories for CVE-2026-27469 (1)

IV. Related Vulnerabilities

Same weakness: CWE-79

V. Comments for CVE-2026-27469

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