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Fencer Intel
medium 6.1

CVE-2026-120633 json

CGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port

published 6d ago modified 7h ago also EUVD-2026-116600

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • cpan CGI 5.00
  • perl-CGI openSUSE Tumbleweed 5.20.0-1.1

opensuse advisories openSUSE-SU-2026:12465-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-120633 updated cvss 6.1

perl-CGI: perl-CGI: Web cache poisoning and URL manipulation via untrusted host headers

  • Red Hat Enterprise Linux 7 perl-CGI 4.61-5.el10 Red Hat Enterprise Linux 8 perl-CGI 4.61-5.el10 Red Hat Enterprise Linux 9 perl-CGI 4.61-5.el10 Red Hat Enterprise Linux 10 perl-CGI 4.61-5.el10
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7h ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

  • cpan CGI

Classification

Weakness
  • CWE-348 Use of Less Trusted Source
  • CWE-601 URL Redirection to Untrusted Site

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.