{"answers":{"affected":"2 open source packages ship an affected version, including mdex and mdex_native.","exploited":"There is no known exploitation of CVE-2026-53427 in the wild and no public exploit code.","fix":"Upgrade mdex to 0.12.3 or later.","what":"CVE-2026-53427 is a low-severity cross-site scripting vulnerability in leandrocp mdex, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-53427 and fix it if it is affected.\n\nWhat it is: CVE-2026-53427 is a low-severity cross-site scripting vulnerability in leandrocp mdex, published on 29 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.\nExploitation: There is no known exploitation of CVE-2026-53427 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- mdex (Hex): affected from 0.11.3; fixed in 0.12.3\n- mdex_native (Hex): affected from 0.1.0; fixed in 0.2.3\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-53427/ (Markdown: https://insights.sbomify.com/CVE-2026-53427/index.md)","id":"CVE-2026-53427","markdown":"https://insights.sbomify.com/CVE-2026-53427/index.md","name":"CVE-2026-53427","record":{"aliases":["EEF-CVE-2026-53427","GHSA-v664-pmxr-mxxx"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["account_takeover","code_execution"],"network_reachable":"yes","non_default_config":true,"product_category":"Elixir Markdown library","requires_auth":"none","summary":"Attackers can inject arbitrary JavaScript via Markdown code fences when specific rendering options are enabled, leading to session theft and account takeover.","user_interaction":"required","vuln_class":"xss"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"EEF","cpe":[],"cvss":{"score":2.3,"severity":"low","source":"cna","vector":"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"},"cwes":[{"id":"CWE-79","name":"Improper Neutralization of Input During Web Page Generation"}],"description":"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 \u003cdiv\u003e. A single-quoted shell token preserves an inner double quote through shlex parsing, so a value such as '\"\u003e\u003cscript\u003ealert(1)\u003c/script\u003e' 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.","ecosystems":["Hex"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"Cross-site scripting in MDEx via unescaped highlight_lines_class code-fence attribute","id":"CVE-2026-53427","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Hex","product":null,"products":[],"type":"xss","year":"2026"},"n_packages":2,"n_references":4,"next":{"headline":"Unbounded memory allocation in highlight_lines range expansion in mdex","id":"CVE-2026-53428"},"packages":[{"ecosystem":"Hex","fixed":["0.12.3"],"introduced":["0.11.3"],"last_affected":[],"package":"mdex","purl":"pkg:hex/mdex","source":"EEF-CVE-2026-53427"},{"ecosystem":"Hex","fixed":["0.2.3"],"introduced":["0.1.0"],"last_affected":[],"package":"mdex_native","purl":"pkg:hex/mdex_native","source":"EEF-CVE-2026-53427"}],"prev":{"headline":"Atom-table exhaustion denial-of-service via JSON parse_document in MDEx","id":"CVE-2026-53426"},"products":["mdex","mdex_native"],"published":"2026-06-29","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"Erlang Ecosystem Foundation","prefix":"EEF"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-06-30","vendors":["leandrocp"]},"summary":"Attackers can inject arbitrary JavaScript via Markdown code fences when specific rendering options are enabled, leading to session theft and account takeover.","url":"https://insights.sbomify.com/CVE-2026-53427/"}