Bug 2566594 (CVE-2026-120633)

Summary: CVE-2026-120633 perl-CGI: perl-CGI: Web cache poisoning and URL manipulation via untrusted host headers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in perl-CGI. This vulnerability allows a remote attacker to conduct web cache poisoning or redirect users to malicious websites by sending crafted Hypertext Transfer Protocol (HTTP) requests with untrusted host headers. Because the module trusts client-provided headers such as X-Forwarded-Host to construct internal addresses and redirects without proper validation, an attacker can manipulate generated links to point to an external system under their control.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-11-03 23:51:29 UTC 
CGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port.

These 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.

A client can poison shared caches, and URLs the application stores or sends, with redirects, links and scripts that point at a host it controls.