{"id":"CVE-2026-120633","title":"CGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port","summary":"CGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port.\n\nThese take the host name and port from the X-Forwarded-Host request header when present, and otherwise from Host…","severity":"none","cwe":["CWE-348","CWE-601"],"product":"CGI","affected":["CGI < 5.00"],"published":"2026-11-03","updated":"2026-11-03","sourceUpdated":"2026-11-03T23:40:04.604Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-120633","references":[{"url":"https://metacpan.org/release/LEEJO/CGI-4.72/source/lib/CGI.pm"},{"url":"https://metacpan.org/release/LEEJO/CGI-5.00/changes"},{"url":"https://github.com/leejo/CGI.pm/commit/d76752a5e8dfd365b0fe3a0b9a7da6c054e856af.patch"}],"tags":["cve.org"],"epss":0.00131,"epssPercentile":0.02694,"ingestedAt":"2026-11-05T20:33:06.614Z","slug":"CVE-2026-120633","body":"## Overview\n\nCGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port.\n\nThese take the host name and port from the X-Forwarded-Host request header when present, and otherwise from Host, without validating either. The URLs from url and self_url are the default redirect location and the start_html(-base=>1) base href, and the default start_form action when REQUEST_URI is not set.\n\nA client can poison shared caches, and URLs the application stores or sends, with redirects, links and scripts that point at a host it controls.\n\n## Affected\n\n- `CGI < 5.00`\n\n## Remediation\n\nUpgrade to CGI 5.00 or later.\n\n### Workarounds\n\nFor deployments that cannot upgrade, strip X-Forwarded-Host at the web server or proxy unless it sets the header itself, and validate Host.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}