{"answers":{"affected":"2 open source packages ship an affected version, including league/commonmark.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-71478 exists.","fix":"Upgrade league/commonmark to 2.9.0 or later.","what":"CVE-2026-71478 is a medium-severity cross-site scripting vulnerability in thephpleague commonmark, published on 6 Aug 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-2026-71478 and fix it if it is affected.\n\nWhat it is: CVE-2026-71478 is a medium-severity cross-site scripting vulnerability in thephpleague commonmark, published on 6 Aug 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-71478 exists.\n\nAffected packages and fixed versions:\n- league/commonmark (Packagist): affected from 1.5.0; fixed in 2.9.0\n- league/commonmark (Packagist): affected from 1.5.0; fixed in 2.9.0\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-2026-71478/ (Markdown: https://insights.sbomify.com/CVE-2026-71478/index.md)","id":"CVE-2026-71478","markdown":"https://insights.sbomify.com/CVE-2026-71478/index.md","name":"CVE-2026-71478","record":{"aliases":["DEBIAN-CVE-2026-71478","GHSA-29pj-957v-52mc","UBUNTU-CVE-2026-71478"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["code_execution"],"network_reachable":"yes","non_default_config":false,"product_category":"PHP Markdown library","requires_auth":"none","summary":"Attackers can bypass unsafe-link filters in league/commonmark to inject JavaScript via control bytes, leading to XSS in rendered Markdown.","user_interaction":"required","vuln_class":"xss"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[],"cvss":{"score":6.1,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-86","name":"Improper Neutralization of Invalid Characters in Identifiers in Web Pages"},{"id":"CWE-79","name":"Improper Neutralization of Input During Web Page Generation"},{"id":"CWE-692","name":"Incomplete Denylist to Cross-Site Scripting"}],"description":"league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.","ecosystems":["Packagist"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"league/commonmark: AttributesExtension href/src unsafe-link filter bypass via embedded control bytes","id":"CVE-2026-71478","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Packagist","product":null,"products":[],"type":"xss","year":"2026"},"n_packages":2,"n_references":3,"next":{"headline":"New API: Integer overflow in quota billing yields negative charges (self-crediting)","id":"CVE-2026-71479"},"packages":[{"ecosystem":"Packagist","fixed":["2.9.0"],"introduced":["1.5.0"],"last_affected":[],"package":"league/commonmark","purl":null,"source":"GHSA-29pj-957v-52mc"},{"ecosystem":"Packagist","fixed":["2.9.0"],"introduced":["1.5.0"],"last_affected":[],"package":"league/commonmark","purl":"pkg:composer/league/commonmark","source":"GHSA-29pj-957v-52mc"}],"prev":{"headline":"mise: Incorrect file ownership, when installed by the root user using `install.sh`","id":"CVE-2026-71477"},"products":["commonmark"],"published":"2026-08-06","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-08-07","vendors":["thephpleague"]},"summary":"Attackers can bypass unsafe-link filters in league/commonmark to inject JavaScript via control bytes, leading to XSS in rendered Markdown.","url":"https://insights.sbomify.com/CVE-2026-71478/"}