{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43969", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-05-04T18:23:25.573Z", "datePublished": "2026-05-11T18:06:40.667Z", "dateUpdated": "2026-05-11T18:55:26.121Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["cow_cookie"], "packageName": "cowlib", "packageURL": "pkg:hex/cowlib", "product": "cowlib", "programFiles": ["src/cow_cookie.erl"], "programRoutines": [{"name": "cow_cookie:cookie/1"}], "repo": "https://github.com/ninenines/cowlib", "vendor": "ninenines", "versions": [{"status": "affected", "version": "2.9.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["cow_cookie"], "packageName": "ninenines/cowlib", "packageURL": "pkg:github/ninenines/cowlib", "product": "cowlib", "programFiles": ["src/cow_cookie.erl"], "programRoutines": [{"name": "cow_cookie:cookie/1"}], "repo": "https://github.com/ninenines/cowlib", "vendor": "ninenines", "versions": [{"status": "affected", "version": "f017f8a0ecbffd5033d9ab49bf180186f7a523a7", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>The application must pass attacker-controlled bytes as cookie names or values to <tt>cow_cookie:cookie/1</tt>. Applications that construct cookie lists exclusively from trusted, application-controlled values are not affected.</p>"}], "value": "The application must pass attacker-controlled bytes as cookie names or values to cow_cookie:cookie/1. Applications that construct cookie lists exclusively from trusted, application-controlled values are not affected."}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.9.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "credits": [{"lang": "en", "type": "finder", "value": "Peter Ullrich"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>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.</p><p><tt>cow_cookie:cookie/1</tt> in cowlib builds a client-side <tt>Cookie:</tt> 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 <tt>;</tt>, <tt>,</tt>, CR, LF, or TAB characters into the serialized header. This enables two classes of attack: cookie smuggling within a single header (e.g. injecting <tt>; admin=1</tt> 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 (<tt>parse_cookie_name/1</tt>, <tt>parse_cookie_value/1</tt>) and <tt>setcookie/3</tt> already validate and reject these characters; the encoder alone is missing the check.</p><p>This issue affects cowlib from 2.9.0.</p>"}], "value": "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.\n\ncow_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.\n\nThis issue affects cowlib from 2.9.0."}], "impacts": [{"capecId": "CAPEC-105", "descriptions": [{"lang": "en", "value": "CAPEC-105 HTTP Request Splitting"}]}], "metrics": [{"cvssV4_0": {"attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "LOCAL", "baseScore": 2.1, "baseSeverity": "LOW", "privilegesRequired": "NONE", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "LOW", "userInteraction": "NONE", "vectorString": "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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-93", "description": "CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-05-11T18:24:59.802Z"}, "references": [{"tags": ["related", "third-party-advisory"], "url": "https://cna.erlef.org/cves/CVE-2026-43969.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-43969"}, {"tags": ["patch"], "url": "https://github.com/erlef/cowlib/commit/177953dd51540da11090666c1f007214127a1144"}], "source": {"discovery": "EXTERNAL"}, "title": "Cookie Request Header Injection via Unvalidated Encoder in cow_cookie:cookie/1", "workarounds": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Validate inputs into <tt>cow_cookie:cookie/1</tt> to only include valid cookie name and value characters as defined in RFC 6265 Section 4.1.1 before passing them to the function.</p>"}], "value": "Validate inputs into cow_cookie:cookie/1 to only include valid cookie name and value characters as defined in RFC 6265 Section 4.1.1 before passing them to the function."}], "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-05-11T18:55:16.028478Z", "id": "CVE-2026-43969", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-11T18:55:26.121Z"}}]}}

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43969", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-05-04T18:23:25.573Z", "datePublished": "2026-05-11T18:06:40.667Z", "dateUpdated": "2026-05-11T18:55:26.121Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["cow_cookie"], "packageName": "cowlib", "packageURL": "pkg:hex/cowlib", "product": "cowlib", "programFiles": ["src/cow_cookie.erl"], "programRoutines": [{"name": "cow_cookie:cookie/1"}], "repo": "https://github.com/ninenines/cowlib", "vendor": "ninenines", "versions": [{"status": "affected", "version": "2.9.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["cow_cookie"], "packageName": "ninenines/cowlib", "packageURL": "pkg:github/ninenines/cowlib", "product": "cowlib", "programFiles": ["src/cow_cookie.erl"], "programRoutines": [{"name": "cow_cookie:cookie/1"}], "repo": "https://github.com/ninenines/cowlib", "vendor": "ninenines", "versions": [{"status": "affected", "version": "f017f8a0ecbffd5033d9ab49bf180186f7a523a7", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>The application must pass attacker-controlled bytes as cookie names or values to <tt>cow_cookie:cookie/1</tt>. Applications that construct cookie lists exclusively from trusted, application-controlled values are not affected.</p>"}], "value": "The application must pass attacker-controlled bytes as cookie names or values to cow_cookie:cookie/1. Applications that construct cookie lists exclusively from trusted, application-controlled values are not affected."}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.9.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "credits": [{"lang": "en", "type": "finder", "value": "Peter Ullrich"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>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.</p><p><tt>cow_cookie:cookie/1</tt> in cowlib builds a client-side <tt>Cookie:</tt> 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 <tt>;</tt>, <tt>,</tt>, CR, LF, or TAB characters into the serialized header. This enables two classes of attack: cookie smuggling within a single header (e.g. injecting <tt>; admin=1</tt> 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 (<tt>parse_cookie_name/1</tt>, <tt>parse_cookie_value/1</tt>) and <tt>setcookie/3</tt> already validate and reject these characters; the encoder alone is missing the check.</p><p>This issue affects cowlib from 2.9.0.</p>"}], "value": "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.\n\ncow_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.\n\nThis issue affects cowlib from 2.9.0."}], "impacts": [{"capecId": "CAPEC-105", "descriptions": [{"lang": "en", "value": "CAPEC-105 HTTP Request Splitting"}]}], "metrics": [{"cvssV4_0": {"attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "LOCAL", "baseScore": 2.1, "baseSeverity": "LOW", "privilegesRequired": "NONE", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "LOW", "userInteraction": "NONE", "vectorString": "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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-93", "description": "CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-05-11T18:24:59.802Z"}, "references": [{"tags": ["related", "third-party-advisory"], "url": "https://cna.erlef.org/cves/CVE-2026-43969.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-43969"}, {"tags": ["patch"], "url": "https://github.com/erlef/cowlib/commit/177953dd51540da11090666c1f007214127a1144"}], "source": {"discovery": "EXTERNAL"}, "title": "Cookie Request Header Injection via Unvalidated Encoder in cow_cookie:cookie/1", "workarounds": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Validate inputs into <tt>cow_cookie:cookie/1</tt> to only include valid cookie name and value characters as defined in RFC 6265 Section 4.1.1 before passing them to the function.</p>"}], "value": "Validate inputs into cow_cookie:cookie/1 to only include valid cookie name and value characters as defined in RFC 6265 Section 4.1.1 before passing them to the function."}], "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-43969", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-05-11T18:55:16.028478Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-11T18:55:21.472Z"}}]}}

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