FileCodeBox 2.2.1 through 2.8.4 Stored XSS via Markdown Preview Parser Error

Advisories

FileCodeBox 2.2.1 through 2.8.4 Stored XSS via Markdown Preview Parser Error

Severity: medium
Date: 11/13/2026
Affecting: FileCodeBox >= 2.2.1, <= 2.8.4
CVE: CVE-2026-129170
CWE: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS: 5.3
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
References: https://vul.yulun.ac.cn/20261027/filecodebox/
https://github.com/vastsa/FileCodeBox/issues/557
https://github.com/vastsa/FileCodeBoxFronted/commit/4c40406d366af1583a3ba2327366b7a62d765537
https://github.com/vastsa/FileCodeBoxFronted/blob/bcc1dbda06b772d6f4afbcc12c6f12e60bbbc7da/src/utils/content-preview.ts#L43-L57
https://github.com/vastsa/FileCodeBoxFronted/blob/bcc1dbda06b772d6f4afbcc12c6f12e60bbbc7da/src/components/common/ContentPreviewModal.vue#L45-L50
Credit: Wu Yulun
Description: FileCodeBox 2.2.1 through 2.8.4 contains a stored cross-site scripting vulnerability in renderMarkdownPreview, which returns unsanitized text when the marked parser throws. Unauthenticated attackers can share text with thousands of nested blockquote markers followed by HTML payloads, executing script that steals the admin token from localStorage.

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