Infinite loop in Perl CGI module on short request bodies
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-835.
Summary
CGI for Perl versions before 5.00 contain an infinite loop caused by a read that never ends (CWE-835). When $CGI::DISABLE_UPLOADS is set, a request body shorter than its Content-Length makes the discard loop spin forever. A client can keep a server process spinning with one such request.
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 an infinite loop on a short request body when $DISABLE_UPLOADS is set. When $CGI::PUTDATA_UPLOAD or an upload hook is set, read_postdata_putdata takes a request body that is not a form submission. With $CGI::DISABLE_UPLOADS set, it discards the body by reading until Content-Length bytes have arrived. Once a body shorter than its Content-Length runs out, every read returns 0, so the loop never ends. A client can keep a server process spinning with one such request.
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 Enterprise Linux 7, 8, 9 and 10 are affected. The sources list no fixed version for them.
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-2026-120651
- 2026-11-04 Affected versions changed · Red Hat
- 2026-11-04 CVSS score added · Red Hat
- 2026-11-04 Alias added: GHSA-hwfw-56x5-6gp9
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score changed · Red Hat
References
Sources
- CVE-2026-120651 · CVE Program
- CVE-2026-120651 · NVD
- FIRST EPSS
- GHSA-hwfw-56x5-6gp9 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-120651 · Red Hat security data · CC BY 4.0
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