CVE-2026-43969

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-43969
Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in ninenines cowlib allows HTTP request splitting and cookie smuggling via unvalidated cookie name and value fields. cow_cookie:cookie/1 in cowlib builds a client-side Cookie: request header from a list of name-value pairs without validating either field. An attacker who controls the cookie names or values passed to this function can inject ;, ,, CR, LF, or TAB characters into the serialized header. This enables two classes of attack: cookie smuggling within a single header (e.g. injecting "; admin=1" to introduce a phantom cookie that the receiving server treats as authentic) and HTTP request header splitting (injecting CRLF to append arbitrary headers or smuggle a complete second request against a shared upstream proxy). The decoder side (parse_cookie_name/1, parse_cookie_value/1) and setcookie/3 already validate and reject these characters; the encoder alone is missing the check. This issue affects cowlib from 2.9.0.

3.2 /10

CVSS v3 : LOW

V3 Legend

Vector :

Exploitability : 1.4 / Impact : 1.4

Attack Vector LOCAL

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References
Link Resource
https://cna.erlef.org/cves/CVE-2026-43969.html Vendor Advisory
https://github.com/erlef/cowlib/commit/177953dd51540da11090666c1f007214127a1144 Patch
https://osv.dev/vulnerability/EEF-CVE-2026-43969 Third Party Advisory
Configurations

Configuration 1 (hide)

cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*
History

21 May 2026, 13:57

Type Values Removed Values Added
CPE cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 3.2
References () https://cna.erlef.org/cves/CVE-2026-43969.html - () https://cna.erlef.org/cves/CVE-2026-43969.html - Vendor Advisory
References () https://github.com/erlef/cowlib/commit/177953dd51540da11090666c1f007214127a1144 - () https://github.com/erlef/cowlib/commit/177953dd51540da11090666c1f007214127a1144 - Patch
References () https://osv.dev/vulnerability/EEF-CVE-2026-43969 - () https://osv.dev/vulnerability/EEF-CVE-2026-43969 - Third Party Advisory
First Time Ninenines cowlib
Ninenines

11 May 2026, 19:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-05-11 19:16

Updated : 2026-05-21 13:57

NVD link : CVE-2026-43969

Mitre link : CVE-2026-43969

CVE.ORG link : CVE-2026-43969

JSON object : View

Products Affected

ninenines

  • cowlib
CWE
CWE-93

Improper Neutralization of CRLF Sequences ('CRLF Injection')