CGI for Perl lets form fields bypass proxies and WAFs via multipart parsing
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 4 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
CGI for Perl versions before 5.00 parse multipart/form-data differently from the RFCs. The parser matches the boundary anywhere rather than at the start of a line, accepts the boundary without its leading -- for some client-supplied User-Agent values, finds Content-Disposition name and filename inside the quoted values of other parameters, and corrupts parts when the boundary nears the 4096-byte read size. An attacker can smuggle form fields past proxies and WAFs. The weakness is CWE-436 (Interpretation Conflict).
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 form fields to be smuggled past proxies and WAFs via multipart parsing that differs from the RFCs. The multipart/form-data parser matches the boundary anywhere rather than at the start of a line, uses the boundary without its leading -- for some client-supplied User-Agent values, finds the Content-Disposition name and filename inside the quoted values of other parameters, and corrupts parts when the boundary nears the 4096-byte read size.
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 for Perl to version 5.00 or later. Red Hat rates this issue Moderate, and no fix is currently available for Red Hat Enterprise Linux 7, 8, 9 or 10.
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-2026-120635
- 2026-11-04 Affected versions changed · Red Hat
- 2026-11-04 CVSS score added · Red Hat
- 2026-11-04 Alias added: GHSA-hc7g-hfjx-mc5f
References
Patch 4
- https://github.com/leejo/CGI.pm/commit/f719fc08e8756708bcd4f1e357d5c0f8702f85dd.patch
- https://github.com/leejo/CGI.pm/commit/cbf04979f9974458ac223793bbd9d0b6a772aa66.patch
- https://github.com/leejo/CGI.pm/commit/fe9516804d59a3774e280c15dbb7072fbd0ba5f1.patch
- https://github.com/leejo/CGI.pm/commit/e0ef8f4248c6ae3025749040d8595d206b6a1b49.patch
Sources
- CVE-2026-120635 · CVE Program
- CVE-2026-120635 · NVD
- FIRST EPSS
- GHSA-hc7g-hfjx-mc5f · GitHub Advisory Database · CC BY 4.0
- CVE-2026-120635 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences