CVE-2026-120635: Libcgi pm perl · CGI versions before 5.00 for Perl allow form fields to be smuggled past proxies and
Affects libcgi-pm-perlSource GCVE Database
Not known to be exploited · CVSS 8.1 High.
Data as of 12 Nov 2026, 22:05 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 8.1 |
|---|
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HExploitation 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 12 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10libcgi-pm-perlpkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlibcgi-pm-perlpkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlibcgi-pm-perlpkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlibcgi-pm-perlpkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 20.04 LTSlibcgi-pm-perlpkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=focalOther threats | Affected
| Fixed in– |
Ubuntu 18.04 LTSlibcgi-pm-perlpkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=bionicOther 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
Until a fix is available, users should consider additional proxy and WAF configurations to detect or block malformed multipart/form-data requests that exploit this parsing flaw.
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). The parser incorrectly matches boundaries anywhere instead of at the start of a line, misuses the boundary string without its leading '--' for certain User-Agent values, and misinterprets Content-Disposition parameters. Additionally, it corrupts parts when the boundary approaches the 4096-byte read size. This flaw can lead to high-impact confidentiality and availability issues.
References
- ubuntu.com/security/CVE-2026-120635 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-120635 (opens in a new tab)
- lists.security.metacpan.org/cve-announce/msg/44874788/ (opens in a new tab)
- github.com/leejo/CGI.pm/commit/f719fc08e8756708bcd4f1e357d5c0f8702f85dd (opens in a new tab)
- github.com/leejo/CGI.pm/commit/cbf04979f9974458ac223793bbd9d0b6a772aa66 (opens in a new tab)
- github.com/leejo/CGI.pm/commit/fe9516804d59a3774e280c15dbb7072fbd0ba5f1 (opens in a new tab)
- github.com/leejo/CGI.pm/commit/e0ef8f4248c6ae3025749040d8595d206b6a1b49 (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)