Deep Chat through 2.5.1 XSS via Markdown Link Validation Bypass

Advisories

Deep Chat through 2.5.1 XSS via Markdown Link Validation Bypass

severity: low
date: 10/11/2026
Affecting: Deep Chat >= 1.4.7, <= 2.5.1
CVE: CVE-2026-108852
CWE: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS: 2.1
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
References: https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/ovidijusparsiunas-deep-chat-markdown-scheme-validation
https://github.com/OvidijusParsiunas/deep-chat/blob/2.5.1/component/src/views/chat/messages/remarkable/remarkableConfig.ts#L74-L78
https://github.com/OvidijusParsiunas/deep-chat
Credit: hieuPenguinnn
Description: Deep Chat through 2.5.1 contains a cross-site scripting vulnerability that allows attackers to inject javascript: links because RemarkableConfig.createNew disables Remarkable link validation. Attackers can place crafted Markdown links in AI responses, addMessage content, or loaded history to execute script in the embedding page when victims click them.

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