Backtracking regex in Perl CGI lets attackers exhaust CPU
Key facts
- Attack vector
- —
- Privileges required
- —
- User interaction
- —
- Attack complexity
- —
- Impact type
- Denial of service
- 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-1333.
Summary
CGI versions from 0 before 5.00 for Perl are affected. The module parses the boundary and start parameters of a POST multipart/related Content-Type with an unanchored regular expression that backtracks in cubic time (CWE-1333) when the header does not match. An attacker can exhaust CPU with a crafted Content-Type header, and no request body is needed.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
CGI versions before 5.00 for Perl allow CPU exhaustion via a backtracking regex on the XForms multipart/related Content-Type. When a POST Content-Type contains multipart/related, the boundary and start parameters are extracted with an unanchored pattern that puts .+ on either side of the boundary capture, which backtracks in cubic time on a header that does not match. No request body is needed.
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. Red Hat's plan for Red Hat Enterprise Linux 7, 8, 9 and 10 is none available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- 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-2026-120632
- 2026-11-04 Affected versions changed · Red Hat
- 2026-11-04 CVSS score added · Red Hat
- 2026-11-04 Alias added: GHSA-94q2-8552-36r5
References
Sources
- CVE-2026-120632 · CVE Program
- CVE-2026-120632 · NVD
- FIRST EPSS
- GHSA-94q2-8552-36r5 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-120632 · Red Hat security data · CC BY 4.0
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