CVE-2026-120635: CGI versions before 5.00 for Perl allow form fields to be smuggled past proxies and WAFs via
Source GCVE Database
Not known to be exploited : upgrade to 5.00 soon.
Data as of 4 Nov 2026, 02:00 UTC
Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD
Thin evidence
One scorer or none- Patch
- Available – fixed in 5.00
Exploitation evidence
Disclosed: evidence found.
CVE published 3 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.
What to do
Upgrade CGI (Perl module) to 5.00.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| CGI | Affected
| Fixed in
|
CPANCGIpkg:cpan/CGIOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, users should consider additional protective measures at the network or application level to detect or block malformed multipart/form-data requests.
Description
CGI versions before 5.00 for Perl contain a vulnerability in their multipart/form-data parser that allows form fields to be smuggled past proxies and web application firewalls (WAFs). This occurs because the parser matches boundaries incorrectly, uses boundaries without the leading '--' for certain User-Agent values, misinterprets Content-Disposition parameters, and corrupts parts near the 4096-byte read size.
References
- nvd.nist.gov/vuln/detail/CVE-2026-120635 (opens in a new tab)
- github.com/leejo/CGI.pm/commit/cbf04979f9974458ac223793bbd9d0b6a772aa66.patch (opens in a new tab)
- github.com/leejo/CGI.pm/commit/e0ef8f4248c6ae3025749040d8595d206b6a1b49.patch (opens in a new tab)
- github.com/leejo/CGI.pm/commit/f719fc08e8756708bcd4f1e357d5c0f8702f85dd.patch (opens in a new tab)
- github.com/leejo/CGI.pm/commit/fe9516804d59a3774e280c15dbb7072fbd0ba5f1.patch (opens in a new tab)
- metacpan.org/release/LEEJO/CGI-4.72/source/lib/CGI.pm (opens in a new tab)
- metacpan.org/release/LEEJO/CGI-5.00/changes (opens in a new tab)
- rfc-editor.org/rfc/rfc2046 (opens in a new tab)