CVE-2026-105786

Joplin version 2.8.8 contains a vulnerability that allows arbitrary command execution. The attack is performed by injecting a crafted payload into note titles.

In Joplin prior to 3.7.13, selecting a note containing a jsoncanvas fence causes the whiteboard text and file-node components to render card content with the full Markdown renderer, and the components insert the resulting HTML into the main application document through dangerouslySetInnerHTML. A malicious note can inject style elements and remote CSS imports that modify trusted application chrome, signal when the note is opened, and potentially disclose exposed attribute values. Content Security Policy blocks inline script execution, so the supported impact is CSS injection and UI redressing rather than code execution. This issue is fixed in version 3.7.13.

Joplin is an open source note-taking and to-do application. Prior to 3.7.13, when Joplin Desktop is running with the opt-in Web Clipper server enabled, the server in packages/lib/ClipperServer.ts sends Access-Control-Allow-Origin: * and allows an arbitrary website to call POST /auth and GET /auth/check because the pairing endpoints do not reject HTTP or HTTPS origins. The desktop confirmation dialog does not identify the requesting origin, so a victim who approves the generic prompt authorizes the attacking page, which then receives the permanent API token. The token provides ongoing read and write access to notes, folders, tags, resources, and master keys. This issue is fixed in version 3.7.13.

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, and demonstrated execution requires middle-click or Open in new tab in an older or non-hardened browser.

Joplin, an open source note-taking and to-do application, prior to versions 3.6.15 and 3.7.2, passes HTML generated by the vendored fountain.js renderer into note output without sanitizing it. A malicious Fountain code block can execute script when Fountain rendering is enabled in desktop or mobile clients, or when a note is published through Joplin Server where Fountain rendering is enabled by default.

Joplin, an open source note-taking and to-do application, prior to versions 3.6.15 and 3.7.2, accepts synchronized resource metadata whose id or file_extension contains parent-directory or path-separator characters. During background synchronization, ResourceFetcher writes the attacker-controlled resource blob outside the resource directory, allowing creation or overwriting of files at an attacker-chosen existing path.

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.

Joplin versions 3.5.2 and earlier contain a logic error in the delta API that allows share recipients to download notes that are no longer shared with them. The flaw stems from improper filtering of item state and change compression, leading to data leakage.

Joplin, an open-source note-taking and to-do application, versions 3.6.14 and prior, contains a Denial of Service (DoS) vulnerability in the note title input due to missing length validation. An attacker can cause an Out Of Memory (OOM) error and program termination by inserting an excessively long string into a note's title, either via the UI or through the local web service API (port 41184) after compromising an authentication token. The issue is fixed in version 3.7.1.

Joplin prior to version 3.5.7 contains a path traversal vulnerability in the importer, allowing arbitrary file overwrite. The OneNote converter does not sanitize embedded file names, enabling ../.. sequences.