{"containers":{"cna":{"affected":[{"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.MDEx'","comrak_nif"],"packageName":"mdex","packageURL":"pkg:hex/mdex","product":"mdex","programFiles":["native/comrak_nif/src/lumis_adapter.rs"],"programRoutines":[{"name":"comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"},{"name":"comrak_nif::lumis_adapter::LumisAdapter::highlight_lines_config"},{"name":"comrak_nif::lumis_adapter::LumisAdapter::write_highlighted"},{"name":"'Elixir.MDEx':to_html/2"}],"repo":"https://github.com/leandrocp/mdex","vendor":"leandrocp","versions":[{"lessThan":"0.12.3","status":"affected","version":"0.11.3","versionType":"semver"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.MDEx'","comrak_nif"],"packageName":"leandrocp/mdex","packageURL":"pkg:github/leandrocp/mdex","product":"mdex","programFiles":["native/comrak_nif/src/lumis_adapter.rs"],"programRoutines":[{"name":"comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"},{"name":"comrak_nif::lumis_adapter::LumisAdapter::highlight_lines_config"},{"name":"comrak_nif::lumis_adapter::LumisAdapter::write_highlighted"},{"name":"'Elixir.MDEx':to_html/2"}],"repo":"https://github.com/leandrocp/mdex","vendor":"leandrocp","versions":[{"lessThan":"6ed94d905f97af188323f042698ae841c02293b4","status":"affected","version":"0d7ffc84ea742e1daf666426814e5bb6d0499433","versionType":"git"}]},{"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:leandrocp:mdex_native:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.MDExNative.Comrak'","mdex_native_nif"],"packageName":"mdex_native","packageURL":"pkg:hex/mdex_native","product":"mdex_native","programFiles":["native/mdex_native_nif/src/lumis_adapter.rs"],"programRoutines":[{"name":"mdex_native_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"},{"name":"mdex_native_nif::lumis_adapter::LumisAdapter::highlight_lines_config"},{"name":"mdex_native_nif::lumis_adapter::LumisAdapter::write_highlighted"},{"name":"'Elixir.MDExNative.Native':document_to_html_with_options/2"},{"name":"'Elixir.MDExNative.Comrak':document_to_html/2"}],"repo":"https://github.com/leandrocp/mdex_native","vendor":"leandrocp","versions":[{"lessThan":"0.2.3","status":"affected","version":"0.1.0","versionType":"semver"}]},{"collectionURL":"https://github.com","cpes":["cpe:2.3:a:leandrocp:mdex_native:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","modules":["'Elixir.MDExNative.Comrak'","mdex_native_nif"],"packageName":"leandrocp/mdex_native","packageURL":"pkg:github/leandrocp/mdex_native","product":"mdex_native","programFiles":["native/mdex_native_nif/src/lumis_adapter.rs"],"programRoutines":[{"name":"mdex_native_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"},{"name":"mdex_native_nif::lumis_adapter::LumisAdapter::highlight_lines_config"},{"name":"mdex_native_nif::lumis_adapter::LumisAdapter::write_highlighted"},{"name":"'Elixir.MDExNative.Native':document_to_html_with_options/2"},{"name":"'Elixir.MDExNative.Comrak':document_to_html/2"}],"repo":"https://github.com/leandrocp/mdex_native","vendor":"leandrocp","versions":[{"lessThan":"798a363b4339f6f7162ec8437c4c9f9b5ae6fbf3","status":"affected","version":"956528c5e31746253347029e810a969ab916fd27","versionType":"git"}]}],"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>The vulnerable code path is only reachable when MDEx is configured with a syntax-highlighting formatter (for example <tt>syntax_highlight: [formatter: {:html_inline, ...}]</tt> or <tt>{:html_linked, ...}</tt>) and with full info-string forwarding enabled (<tt>render: [full_info_string: true]</tt>). Full info-string forwarding is required for comrak to hand the <tt>highlight_lines_class</tt> attribute to the highlighter, so any application that uses the line-highlighting attributes already has it enabled.</p>"}],"value":"The vulnerable code path is only reachable when MDEx is configured with a syntax-highlighting formatter (for example syntax_highlight: [formatter: {:html_inline, ...}] or {:html_linked, ...}) and with full info-string forwarding enabled (render: [full_info_string: true]). Full info-string forwarding is required for comrak to hand the highlight_lines_class attribute to the highlighter, so any application that uses the line-highlighting attributes already has it enabled."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*","versionEndExcluding":"0.12.3","versionStartIncluding":"0.11.3","vulnerable":true}],"negate":false,"operator":"AND"},{"cpeMatch":[{"criteria":"cpe:2.3:a:leandrocp:mdex_native:*:*:*:*:*:*:*:*","versionEndExcluding":"0.2.3","versionStartIncluding":"0.1.0","vulnerable":true}],"negate":false,"operator":"AND"}],"operator":"OR"}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Leandro Pereira"},{"lang":"en","type":"analyst","value":"Jonatan Männchen / EEF"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>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.</p><p>When syntax highlighting and full info-string forwarding (<tt>render: [full_info_string: true]</tt>) are enabled, the Lumis adapter copies the value of a code fence's <tt>highlight_lines_class</tt> info-string attribute, unescaped, into the <tt>class</tt> attribute of every rendered line. <tt>comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes</tt> in <tt>native/comrak_nif/src/lumis_adapter.rs</tt> shlex-parses the info string and stores each <tt>key=value</tt> pair verbatim, <tt>highlight_lines_config</tt> pulls <tt>highlight_lines_class</tt> into the per-line class value, and <tt>write_highlighted</tt> interpolates that value directly into the <tt>class</tt> attribute of the per-line <tt>&lt;div&gt;</tt>. A single-quoted shell token preserves an inner double quote through shlex parsing, so a value such as <tt>'&quot;&gt;&lt;script&gt;alert(1)&lt;/script&gt;'</tt> terminates the <tt>class</tt> attribute early and the markup that follows is emitted as live HTML.</p><p>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.</p><p>The vulnerable native code originally shipped inside <tt>mdex</tt> (in <tt>native/comrak_nif/src/lumis_adapter.rs</tt>) and was later extracted into the separate <tt>mdex_native</tt> package (<tt>native/mdex_native_nif/src/lumis_adapter.rs</tt>), where it remains unpatched.</p><p>This issue affects mdex from 0.11.3 before 0.12.3, and mdex_native from 0.1.0 before 0.2.3.</p>"}],"value":"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.\n\nWhen 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 <div>. A single-quoted shell token preserves an inner double quote through shlex parsing, so a value such as '\"><script>alert(1)</script>' terminates the class attribute early and the markup that follows is emitted as live HTML.\n\nAn 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.\n\nThe 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.\n\nThis issue affects mdex from 0.11.3 before 0.12.3, and mdex_native from 0.1.0 before 0.2.3."}],"impacts":[{"capecId":"CAPEC-63","descriptions":[{"lang":"en","value":"CAPEC-63 Cross-Site Scripting (XSS)"}]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":2.3,"baseSeverity":"LOW","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","userInteraction":"PASSIVE","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","description":"CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-06-29T18:50:17.185Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["vendor-advisory","related"],"url":"https://github.com/leandrocp/mdex_native/security/advisories/GHSA-v664-pmxr-mxxx"},{"tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-53427.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-53427"},{"tags":["patch"],"url":"https://github.com/leandrocp/mdex_native/commit/798a363b4339f6f7162ec8437c4c9f9b5ae6fbf3"}],"source":{"discovery":"EXTERNAL"},"title":"Cross-site scripting in MDEx via unescaped highlight_lines_class code-fence attribute","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>Do not enable full info-string forwarding (<tt>render: [full_info_string: true]</tt>) when rendering untrusted Markdown, which prevents the <tt>highlight_lines_class</tt> attribute from reaching the highlighter. Alternatively, restrict <tt>highlight_lines_class</tt> values to a safe character set (for example <tt>[A-Za-z0-9_- ]</tt>) before rendering.</p>"}],"value":"Do not enable full info-string forwarding (render: [full_info_string: true]) when rendering untrusted Markdown, which prevents the highlight_lines_class attribute from reaching the highlighter. Alternatively, restrict highlight_lines_class values to a safe character set (for example [A-Za-z0-9_- ]) before rendering."}],"x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-53427","datePublished":"2026-06-29T18:50:17.185Z","dateReserved":"2026-06-09T11:01:47.529Z","dateUpdated":"2026-06-29T18:50:17.185Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}