{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-66835", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-08-17T12:00:02.063Z", "datePublished": "2026-09-01T14:49:47.805Z", "dateUpdated": "2026-09-01T14:49:47.805Z"}, "containers": {"cna": {"affected": [{"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["mod_auth", "mod_alias", "httpd_request"], "packageName": "otp", "packageURL": "pkg:sid/erlang.org/otp", "product": "OTP", "programFiles": ["lib/inets/src/http_server/mod_auth.erl", "lib/inets/src/http_server/mod_alias.erl", "lib/inets/src/http_server/httpd_request.erl"], "programRoutines": [{"name": "mod_auth:secret_path/3"}, {"name": "mod_alias:real_name/3"}, {"name": "httpd_request:validate_uri/1"}], "vendor": "Erlang", "versions": [{"lessThan": "17.0", "status": "unknown", "version": "0", "versionType": "otp"}, {"lessThan": "27.3.4.17", "status": "affected", "version": "17.0", "versionType": "otp"}, {"lessThan": "28.5.0.6", "status": "affected", "version": "28.0", "versionType": "otp"}, {"lessThan": "29.0.6", "status": "affected", "version": "29.0", "versionType": "otp"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["mod_auth", "mod_alias", "httpd_request"], "packageName": "inets", "packageURL": "pkg:otp/inets", "product": "OTP", "programFiles": ["src/http_server/mod_auth.erl", "src/http_server/mod_alias.erl", "src/http_server/httpd_request.erl"], "programRoutines": [{"name": "mod_auth:secret_path/3"}, {"name": "mod_alias:real_name/3"}, {"name": "httpd_request:validate_uri/1"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"lessThan": "5.10", "status": "unknown", "version": "0", "versionType": "otp"}, {"lessThan": "9.3.2.7", "status": "affected", "version": "5.10", "versionType": "otp"}, {"lessThan": "9.6.2.3", "status": "affected", "version": "9.4", "versionType": "otp"}, {"lessThan": "9.7.2", "status": "affected", "version": "9.7", "versionType": "otp"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["mod_auth", "mod_alias", "httpd_request"], "packageName": "erlang/otp", "packageURL": "pkg:github/erlang/otp", "product": "OTP", "programFiles": ["lib/inets/src/http_server/mod_auth.erl", "lib/inets/src/http_server/mod_alias.erl", "lib/inets/src/http_server/httpd_request.erl"], "programRoutines": [{"name": "mod_auth:secret_path/3"}, {"name": "mod_alias:real_name/3"}, {"name": "httpd_request:validate_uri/1"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "bac19eb3dbd96cc49b6d8cabc1c04248bf8c79f6", "status": "unaffected"}, {"at": "d8878dec0ececc2eab18e47bb18b472f224ca633", "status": "unaffected"}, {"at": "9641944a2efbf55bea760f8ff7ba777fe3a0961c", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "84adefa331c4159d432d22840663c38f155cd4c1", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Only servers that protect a directory with <code>mod_auth</code>, by configuring a <code>directory</code> block with authentication requirements, are affected. A server that serves no authenticated directory has no protection for this issue to bypass.</p>"}, {"base64": false, "type": "text/markdown", "value": "Only servers that protect a directory with `mod_auth`, by configuring a `directory` block with authentication requirements, are affected. A server that serves no authenticated directory has no protection for this issue to bypass."}], "value": "Only servers that protect a directory with mod_auth, by configuring a directory block with authentication requirements, are affected. A server that serves no authenticated directory has no protection for this issue to bypass."}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "27.3.4.17", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "28.5.0.6", "versionStartIncluding": "28.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "29.0.6", "versionStartIncluding": "29.0", "vulnerable": true}], "negate": false, "operator": "OR"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "reporter", "value": "Arthur Chan / Ada Logics"}, {"lang": "en", "type": "reporter", "value": "David Korczynski / Ada Logics"}, {"lang": "en", "type": "reporter", "value": "Adam Korczynski / Ada Logics"}, {"lang": "en", "type": "remediation developer", "value": "Konrad Pietrzak / Ericsson"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a <code>mod_auth</code> protected directory by prefixing the request path with an extra slash.</p>\n<p><code>httpd_request:validate_uri/1</code> normalises the request URI with <code>uri_string:normalize/1</code>, which performs RFC 3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives. <code>mod_alias:real_name/3</code> concatenates the document root with that URI, and <code>mod_auth:secret_path/3</code> then decides whether the result lies inside a protected <code>directory</code> block by running the configured directory path as an unanchored regular expression against it. The doubled slash breaks the contiguous substring the regex needs, so the request is treated as unprotected and no authentication challenge is issued, while <code>mod_get</code> opens the same path and the operating system collapses the doubled slash and returns the protected file. The same path mismatch also evades the per-path accounting in <code>mod_security</code>.</p>\n<p>This issue affects OTP from OTP&nbsp;17.0 before OTP&nbsp;27.3.4.17, from OTP&nbsp;28.0 before OTP&nbsp;28.5.0.6, and from OTP&nbsp;29.0 before OTP&nbsp;29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP&nbsp;17.0, corresponding to inets before 5.10, is affected is unknown.</p>"}, {"base64": false, "type": "text/markdown", "value": "Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a `mod_auth` protected directory by prefixing the request path with an extra slash.\n\n`httpd_request:validate_uri/1` normalises the request URI with `uri_string:normalize/1`, which performs RFC 3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives. `mod_alias:real_name/3` concatenates the document root with that URI, and `mod_auth:secret_path/3` then decides whether the result lies inside a protected `directory` block by running the configured directory path as an unanchored regular expression against it. The doubled slash breaks the contiguous substring the regex needs, so the request is treated as unprotected and no authentication challenge is issued, while `mod_get` opens the same path and the operating system collapses the doubled slash and returns the protected file. The same path mismatch also evades the per-path accounting in `mod_security`.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a027.3.4.17, from OTP\u00a028.0 before OTP\u00a028.5.0.6, and from OTP\u00a029.0 before OTP\u00a029.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP\u00a017.0, corresponding to inets before 5.10, is affected is unknown."}], "value": "Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a mod_auth protected directory by prefixing the request path with an extra slash.\n\nhttpd_request:validate_uri/1 normalises the request URI with uri_string:normalize/1, which performs RFC 3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives. mod_alias:real_name/3 concatenates the document root with that URI, and mod_auth:secret_path/3 then decides whether the result lies inside a protected directory block by running the configured directory path as an unanchored regular expression against it. The doubled slash breaks the contiguous substring the regex needs, so the request is treated as unprotected and no authentication challenge is issued, while mod_get opens the same path and the operating system collapses the doubled slash and returns the protected file. The same path mismatch also evades the per-path accounting in mod_security.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a027.3.4.17, from OTP\u00a028.0 before OTP\u00a028.5.0.6, and from OTP\u00a029.0 before OTP\u00a029.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP\u00a017.0, corresponding to inets before 5.10, is affected is unknown."}], "impacts": [{"capecId": "CAPEC-126", "descriptions": [{"lang": "en", "value": "CAPEC-126 Path Traversal"}]}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 8.2, "baseSeverity": "HIGH", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-50", "description": "CWE-50 Path Equivalence: '//multiple/leading/slash'", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-09-01T14:49:47.805Z"}, "references": [{"tags": ["vendor-advisory", "related"], "url": "https://github.com/erlang/otp/security/advisories/GHSA-r4vv-vc2c-2fw6"}, {"tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-66835.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66835"}, {"tags": ["x_version-scheme"], "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions"}, {"tags": ["patch"], "url": "https://github.com/erlang/otp/commit/bac19eb3dbd96cc49b6d8cabc1c04248bf8c79f6"}, {"tags": ["patch"], "url": "https://github.com/erlang/otp/commit/d8878dec0ececc2eab18e47bb18b472f224ca633"}, {"tags": ["patch"], "url": "https://github.com/erlang/otp/commit/9641944a2efbf55bea760f8ff7ba777fe3a0961c"}], "source": {"discovery": "EXTERNAL"}, "title": "httpd mod_auth directory protection bypassed by a doubled slash in the request path"}}}

{}

{}

{}

{}