Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | CGI | < 5.00 | 5.00 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libcgi-pm-perl | No fix yet | — |
| Debian 13 | libcgi-pm-perl | No fix yet | — |
| Debian 12 | libcgi-pm-perl | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libcgi-pm-perl | No fix yet | — |
| Ubuntu 26.04 LTS | libcgi-pm-perl | No fix yet | — |
| Ubuntu 24.04 LTS | libcgi-pm-perl | No fix yet | — |
| Ubuntu 22.04 LTS | libcgi-pm-perl | No fix yet | — |
| Ubuntu 20.04 LTS | libcgi-pm-perl | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libcgi-pm-perl | No fix yet | — |
| Ubuntu 16.04 LTS | libcgi-pm-perl | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | perl-CGI | 5.20.0-1.1 | openSUSE-SU-2026:12465-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | perl-CGI +1 | 5.02-1.amzn2023.0.1 | ALAS2023-2026-3436 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | perl-CGI | No fix yet | — |
Advisories 2
- ALAS2023-2026-3436 Important: perl-CGI security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Nov 12, 2026
- openSUSE-SU-2026:12465-1 perl-CGI-5.20.0-1.1 on GA media SUSE / openSUSE Security Updates · Nov 7, 2026
References
- https://www.rfc-editor.org/rfc/rfc2046#section-5.1.1 technical-description
- https://metacpan.org/release/LEEJO/CGI-4.72/source/lib/CGI.pm technical-description
- https://metacpan.org/release/LEEJO/CGI-5.00/changes release-notes
- https://github.com/leejo/CGI.pm/commit/f719fc08e8756708bcd4f1e357d5c0f8702f85dd.patch patch
- https://github.com/leejo/CGI.pm/commit/cbf04979f9974458ac223793bbd9d0b6a772aa66.patch patch
- https://github.com/leejo/CGI.pm/commit/fe9516804d59a3774e280c15dbb7072fbd0ba5f1.patch patch
- https://github.com/leejo/CGI.pm/commit/e0ef8f4248c6ae3025749040d8595d206b6a1b49.patch patch