CVE-2026-49449: Information Disclosure (CVSS 2.5)

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.

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CVSS v3.1 Score

2.5

LOW

CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.09%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-200 CWE-200

CWE-522 CWE-522

CWE-829 CWE-829

References

Other References

https://github.com/laurent22/joplin/commit/b15472bc9654a72101b34b79c9436b3d450e2c10 https://github.com/laurent22/joplin/pull/15538 https://github.com/laurent22/joplin/security/advisories/GHSA-9m2r-pv96-jxr3

Frequently Asked Questions

What is CVE-2026-49449? +

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. It has a CVSS v3.1 base score of 2.5 (LOW).

How severe is CVE-2026-49449? +

CVE-2026-49449 has a CVSS v3.1 score of 2.5 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-49449? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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