CVE-2026-43969

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Source
https://cve.org/CVERecord?id=CVE-2026-43969
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43969.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-43969
Aliases
Downstream
Published
2026-05-11T18:06:40Z
Modified
2026-10-28T02:31:07Z
Severity
  • 2.1 (Low) CVSS_V4 - CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N CVSS Calculator
Summary
Cookie Request Header Injection via Unvalidated Encoder in cow_cookie:cookie/1
Details

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 before 2.21.0.

Database specific 
{
    "cna_assigner":  "EEF",
    "cwe_ids":  [
        "CWE-93"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43969.json"
}
References

Affected packages

Git / github.com/erlef/cowlib

Affected ranges

Type
GIT
Repo
https://github.com/erlef/cowlib
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
177953dd51540da11090666c1f007214127a1144
Database specific
Show details 
{
    "extracted_events":  [
        {
            "range":  [
                {
                    "fixed":  "177953dd51540da11090666c1f007214127a1144"
                }
            ],
            "source":  "REFERENCES_COMMIT"
        }
    ]
}
Type
GIT
Repo
https://github.com/ninenines/cowlib
Events
Introduced
b34155f725245848dca3a505398e262b1d50f25b
Fixed
c17fd73945ef536cccecc492d286fb6b6d1c3307
Fixed
f017f8a0ecbffd5033d9ab49bf180186f7a523a7
Database specific
Show details 
{
    "extracted_events":  [
        {
            "cpe":  "cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*",
            "range":  [
                {
                    "introduced":  "2.9.0"
                },
                {
                    "last_affected":  "2.16.1"
                }
            ],
            "source":  "CPE_RANGE"
        },
        {
            "range":  [
                {
                    "fixed":  "c17fd73945ef536cccecc492d286fb6b6d1c3307"
                }
            ],
            "source":  "REFERENCES_COMMIT"
        },
        {
            "range":  [
                {
                    "fixed":  "f017f8a0ecbffd5033d9ab49bf180186f7a523a7"
                }
            ],
            "source":  "REFERENCES_COMMIT"
        }
    ]
}

Affected versions

0.*
0.1.0
0.2.0
0.3.0
0.4.0
0.5.0
0.5.1
0.6.0
0.6.1
0.6.2
1.*
1.0.0
1.0.1
1.1.0
1.2.0
1.3.0
2.*
2.0.0
2.0.0-pre.1
2.0.0-rc.1
2.0.1
2.1.0
2.10.0
2.10.1
2.11.0
2.12.0
2.12.1
2.13.0
2.14.0
2.15.0
2.16.0
2.16.1
2.17.0
2.17.1
2.18.0
2.19.0
2.2.0
2.2.1
2.20.0
2.3.0
2.4.0
2.5.0
2.5.1
2.6.0
2.7.0
2.7.1
2.7.2
2.7.3
2.8.0
2.9.0
2.9.1

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43969.json"