CVE-2026-46650: Joplin: Stored XSS in public share viewer via javascript: URL bypass in isAcceptedUrl

Severity: medium (CVSS 4.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-21 · updated 2026-09-29
Weakness: CWE-79

Description

Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Prior to 3.7.2, isAcceptedUrl() in packages/renderer/htmlUtils.ts uses an unanchored regular expression for internal resource URLs, allowing a javascript: URL containing a matching 32-character path fragment to pass validation and be emitted into an HTML note's link. A low-privileged Joplin Server user can publish the crafted HTML note as a public share. In the current build, ordinary left-click is blocked; demonstrated execution requires middle-click or Open in new tab in an older or non-hardened browser because current Chrome and Firefox block javascript: new-tab navigation. When execution succeeds, the script runs in the Joplin Server origin, can read page-visible content, and can make authenticated same-origin requests when the victim is signed in. This issue is fixed in version 3.7.2.

Affected products

laurent22 joplin: before 3.7.2

References

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