Description
CGI versions before 5.00 for Perl allow HTTP header injection via entity decoding after the newline check in header and unchecked values in multipart_start and do_push.
With autoEscape off, header decodes HTML entities in extra header values after its newline check, so an encoded CR or LF reaches the response. multipart_start does not check header values for newlines, and do_push does not check the type it prints in each part.
An application that passes request data into these header values can be made to add headers or split the response.
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://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/69955309d371c8093d11cf12e3ddef491537ffad.patch patch
- https://github.com/leejo/CGI.pm/commit/7733c2753f4f240012097507cda2b6e87ae46db4.patch patch