Open redirect in Perl CGI via HTML entity decoding
Key facts
- Attack vector
- —
- Privileges required
- —
- User interaction
- —
- Attack complexity
- —
- Impact type
- Spoofing
- Confidentiality · integrity · availability
- —
- Fix status
- Partial Red Hat: 4 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat. Impact type from CWE-601.
Summary
CGI for Perl versions before 5.00 decode HTML entities in the redirect URL after the application has validated it, so a validated URL can change meaning. An attacker can craft a URL that passes validation and sends users to another host (CWE-180, CWE-601).
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
Description from the CNA
CGI versions before 5.00 for Perl allow open redirects via HTML entity decoding of the URL after application validation in redirect. redirect decodes HTML entities in its URL before writing the Location header, so a URL the application has already validated can change meaning. For example, //evil.example/ becomes //evil.example/ and sends the user to another host.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | CGI | before 5.00 | 5.00 | Patch available | CNA |
- CGI Vendor— Affected before 5.00 Fixed in 5.00 Patch available CNA
Remediation
Upgrade CGI to version 5.00. Red Hat lists Red Hat Enterprise Linux 7, 8, 9 and 10 as affected, with no fix plan available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-04
- Fix · CNA CGI Fixed in 5.00
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-11-03 Threatist record created from CVE-2026-120638
- 2026-11-04 Affected versions changed · Red Hat
- 2026-11-04 CVSS score added · Red Hat
- 2026-11-04 Alias added: GHSA-33j8-q94p-w495
References
Sources
- CVE-2026-120638 · CVE Program
- CVE-2026-120638 · NVD
- FIRST EPSS
- GHSA-33j8-q94p-w495 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-120638 · Red Hat security data · CC BY 4.0
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