leandrocp mdex/mdex_native up to 0.12.2 lumis_adapter.rs cross site scripting

Summaryinfo

A vulnerability identified as problematic has been detected in leandrocp mdex and mdex_native up to 0.12.2. This impacts an unknown function of the file native/comrak_nif/src/lumis_adapter.rs. Performing a manipulation results in cross site scripting. This vulnerability is identified as CVE-2026-53427. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in leandrocp mdex and mdex_native up to 0.12.2. This affects some unknown functionality of the file native/comrak_nif/src/lumis_adapter.rs. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in leandrocp MDEx allows stored or reflected cross-site scripting via attacker-controlled Markdown. When syntax highlighting and full info-string forwarding (render: [full_info_string: true]) are enabled, the Lumis adapter copies the value of a code fence's highlight_lines_class info-string attribute, unescaped, into the class attribute of every rendered line. comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes in native/comrak_nif/src/lumis_adapter.rs shlex-parses the info string and stores each key=value pair verbatim, highlight_lines_config pulls highlight_lines_class into the per-line class value, and write_highlighted interpolates that value directly into the class attribute of the per-line . A single-quoted shell token preserves an inner double quote through shlex parsing, so a value such as '">alert(1)' terminates the class attribute early and the markup that follows is emitted as live HTML. An attacker who can submit Markdown (through comments, posts, wiki pages, documentation, or any user-generated content) can inject arbitrary HTML and JavaScript that runs in the browser of every user who views the rendered output, enabling session theft, account takeover, and other client-side attacks. No authentication or special privileges are required. The vulnerable native code originally shipped inside mdex (in native/comrak_nif/src/lumis_adapter.rs) and was later extracted into the separate mdex_native package (native/mdex_native_nif/src/lumis_adapter.rs), where it remains unpatched. This issue affects mdex from 0.11.3 before 0.12.3, and mdex_native from 0.1.0 before 0.2.3.

The weakness was released by Peter Ullrich and Jonatan Männchen as GHSA-v664-pmxr-mxxx. It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-53427 since 06/09/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 0.12.3 eliminates this vulnerability. Applying the patch 6ed94d905f97af188323f042698ae841c02293b4 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-40174). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• leandrocp

Name

• mdex
• mdex_native

Version

• 0.12.0
• 0.12.1
• 0.12.2

License

• open-source

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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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