Joplin: KaTeX `trust:true` enables URL-allowlist bypass leading to NTLMv2 credential theft via UNC path on Windows

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-49449
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-21 21:17:03 UTC
Updated2026-09-28 21:17:17 UTC
DescriptionJoplin 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.

Risk And Classification

Primary CVSS: v3.1 2.5 LOW from [email protected]

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

EPSS: 0.001960000 probability, percentile 0.083540000 (date 2026-09-29)

Problem Types: CWE-200 | CWE-522 | CWE-829 | CWE-200 CWE-200: Exposure of Sensitive Information to an Unauthorized Actor | CWE-522 CWE-522: Insufficiently Protected Credentials | CWE-829 CWE-829: Inclusion of Functionality from Untrusted Control Sphere

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary2.5LOWCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
3.1CNADECLARED2.5LOWCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Laurent22 Joplin affected >= 1.4.0, < 3.7.2 Not specified

References

ReferenceSourceLinkTags
github.com/laurent22/joplin/pull/15538 [email protected] github.com
github.com/laurent22/joplin/security/advisories/GHSA-9m2r-pv96-jxr3 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/laurent22/joplin/commit/b15472bc9654a72101b34b79c9436b3d450e2c10 [email protected] github.com
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