Description
Dancer2 versions before 2.2.0 for Perl do not strip CR and LF from response header names in headers_to_array.
The routine removes CR and LF from each header value but not from the name. A name carrying them therefore reaches the PSGI server intact. A server that does not validate keys writes it to the wire, so the bytes after the CRLF arrive as their own header line.
The application has to derive the header name from request data, not just the value.
An attacker who controls that data adds their own headers and splits the response.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | Dancer2 | < 2.2.0 | 2.2.0 |
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 | libdancer2-perl | 2.2.2-1 | — |
| Debian 13 | libdancer2-perl | No fix yet | — |
| Debian 12 | libdancer2-perl | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libdancer2-perl | No fix yet | — |
| Ubuntu 26.04 LTS | libdancer2-perl | No fix yet | — |
| Ubuntu 24.04 LTS | libdancer2-perl | No fix yet | — |
| Ubuntu 22.04 LTS | libdancer2-perl | No fix yet | — |
| Ubuntu 20.04 LTS | libdancer2-perl | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libdancer2-perl | No fix yet | — |
| Ubuntu 16.04 LTS | libdancer2-perl | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | perl-Dancer2 | 2.2.2-1.1 | openSUSE-SU-2026:12202-1 |
Advisories 1
- openSUSE-SU-2026:12202-1 perl-Dancer2-2.2.2-1.1 on GA media SUSE / openSUSE Security Updates · Oct 21, 2026