{"answers":{"affected":"2 open source packages ship an affected version, including justhtml.","exploited":"There is no known exploitation of CVE-2026-5388 in the wild and no public exploit code.","fix":"Upgrade justhtml to 1.15.0 or later.","what":"CVE-2026-5388 is a critical cross-site scripting vulnerability in EmilStenstrom justhtml, published on 23 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-5388 and fix it if it is affected.\n\nWhat it is: CVE-2026-5388 is a critical cross-site scripting vulnerability in EmilStenstrom justhtml, published on 23 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-5388 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- justhtml (PyPI): affected all versions; fixed in 1.15.0\n- justhtml (PyPI): affected all versions; fixed in 1.15.0\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-2026-5388/ (Markdown: https://insights.sbomify.com/CVE-2026-5388/index.md)","id":"CVE-2026-5388","markdown":"https://insights.sbomify.com/CVE-2026-5388/index.md","name":"CVE-2026-5388","record":{"aliases":["GHSA-9ph2-9r4x-rhjp","GHSA-c9vm-hv86-f23r"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["code_execution"],"network_reachable":"yes","non_default_config":true,"product_category":"HTML sanitization library","requires_auth":"none","summary":"Attackers can bypass sanitization to inject malicious HTML and JavaScript via specific configurations or helper APIs in the justhtml library.","user_interaction":"not_required","vuln_class":"xss"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"VulnCheck","cpe":[],"cvss":{"score":9.3,"severity":"critical","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-20","name":"Improper Input Validation"}],"description":"justhtml before 1.15.0 contains multiple security issues in URL sanitization helpers (clean_url_value/clean_url_in_js_string), HTML serialization, Markdown passthrough (html_passthrough=True), and several custom sanitization-policy edge cases. Depending on configuration, an attacker can bypass sanitization to inject active HTML and JavaScript — for example via encoded javascript: URLs, backslash-based relative URLs resolved as remote hosts, markup-breaking programmatic element/attribute names or HTML comments, raw \u003c/textarea\u003e reintroduction through Markdown passthrough, or preserved \u003cstyle\u003e/\u003cmeta http-equiv=refresh\u003e/\u003cbase href\u003e tags in custom policies. Most custom-policy issues do not affect the default sanitize=True configuration; they primarily affect helper APIs, programmatic DOM construction, html_passthrough=True, and custom policies/transform pipelines.","ecosystems":["PyPI"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"justhtml before 1.15.0 Multiple Security Issues","id":"CVE-2026-5388","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"PyPI","product":null,"products":[],"type":"xss","year":"2026"},"n_packages":2,"n_references":2,"next":{"headline":"justhtml before 1.13.0 XSS via code fence breakout","id":"CVE-2026-5389"},"packages":[{"ecosystem":"PyPI","fixed":["1.15.0"],"introduced":["0"],"last_affected":[],"package":"justhtml","purl":null,"source":"GHSA-c9vm-hv86-f23r"},{"ecosystem":"PyPI","fixed":["1.15.0"],"introduced":["0"],"last_affected":[],"package":"justhtml","purl":"pkg:pypi/justhtml","source":"GHSA-c9vm-hv86-f23r"}],"prev":{"headline":"AVEVA Pipeline Simulation Missing Authorization","id":"CVE-2026-5387"},"products":["justhtml"],"published":"2026-08-23","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":"yes","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-08-26","vendors":["EmilStenstrom"]},"summary":"Attackers can bypass sanitization to inject malicious HTML and JavaScript via specific configurations or helper APIs in the justhtml library.","url":"https://insights.sbomify.com/CVE-2026-5388/"}