Dancer2 versions before 2.2.0 for Perl do not strip CR and LF from response header names in headers_to_array

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-93711
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 01:16:55 UTC
Updated2026-09-22 20:17:12 UTC
DescriptionDancer2 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS: 0.002470000 probability, percentile 0.162560000 (date 2026-09-23)

Problem Types: CWE-113 | CWE-113 CWE-113 Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

References

ReferenceSourceLinkTags
www.openwall.com/lists/oss-security/2026/09/22/3 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
github.com/PerlDancer/Dancer2/issues/1822 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
github.com/PerlDancer/Dancer2/commit/ff89ac12af7b8899812a79e9924dfea7a5d... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
metacpan.org/release/CROMEDOME/Dancer2-2.2.0/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2026-09-16T00:00:00.000ZVersion 2.2.0 released with fix.

Solutions

CNA: Upgrade to Dancer2 2.2.0 or later.

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