CVE-2026-49449 Joplin: KaTeX `trust:true` enables URL-allowlist bypass leading to NTLMv2 credential theft via UNC path on Windows
Attackers can steal Windows NTLMv2 credentials by tricking users into clicking malicious links in Joplin notes due to KaTeX trust configuration bypassing URL allowlists.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-49449?
CVE-2026-49449 is a low-severity vulnerability in laurent22 joplin, published on 21 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. From 1.4.0 until 3.7.2, packages/renderer/MdToHtml/rules/katex.ts enables KaTeX's trust option for note content, allowing a note author to place a \href URL into rendered output without passing Joplin's normal URL allowlist. On Windows, clicking a link whose target is an attacker-controlled UNC path causes pathExists() to initiate SMB authentication and disclose the current user's NTLMv2 challenge-response without a warning. The unfiltered URL can also invoke other registered URL handlers, but the credential disclosure through KaTeX \href is the distinguishing demonstrated impact. This issue is fixed in version 3.7.2.
Which versions are affected by CVE-2026-49449?
How do I fix CVE-2026-49449?
No fix has been published for CVE-2026-49449 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-49449 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49449 exists.
Sources
Also known as GHSA-9m2r-pv96-jxr3.