CVE-2026-66835 (GCVE-0-2026-66835)
Vulnerability from cvelistv5 – Published: 2026-09-01 14:49 – Updated: 2026-09-01 17:58
VLAI
EPSS
VEX
Title
httpd mod_auth directory protection bypassed by a doubled slash in the request path
Summary
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.
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.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 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 17.0, corresponding to inets before 5.10, is affected is unknown.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-01 17:57 UTC
CWE
- CWE-50 - Path Equivalence: '//multiple/leading/slash'
Assigner
References
7 references
| URL | Tags |
|---|---|
| https://github.com/erlang/otp/security/advisories… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-66835.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-66835 | related |
| https://www.erlang.org/doc/system/versions.html#o… | x_version-scheme |
| https://github.com/erlang/otp/commit/bac19eb3dbd9… | patch |
| https://github.com/erlang/otp/commit/d8878dec0ece… | patch |
| https://github.com/erlang/otp/commit/9641944a2efb… | patch |
Impacted products
3 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Erlang | OTP |
Unknown:
0 , < 17.0
(otp)
Affected: 17.0 , < 27.3.4.17 (otp) Affected: 28.0 , < 28.5.0.6 (otp) Affected: 29.0 , < 29.0.6 (otp) cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* |
||
| Erlang | OTP |
Unknown:
0 , < 5.10
(otp)
Affected: 5.10 , < 9.3.2.7 (otp) Affected: 9.4 , < 9.6.2.3 (otp) Affected: 9.7 , < 9.7.2 (otp) cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* |
||
| Erlang | OTP |
Affected:
84adefa331c4159d432d22840663c38f155cd4c1 , < *
(git)
cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:* |
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unknown.\"}],\"affected\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"affectedData\":[{\"vendor\":\"Erlang\",\"product\":\"OTP\",\"defaultStatus\":\"unaffected\",\"packageName\":\"otp\",\"cpes\":[\"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\"],\"modules\":[\"mod_auth\",\"mod_alias\",\"httpd_request\"],\"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\"}],\"packageURL\":\"pkg:sid/erlang.org/otp\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"17.0\",\"versionType\":\"otp\",\"status\":\"unknown\"},{\"version\":\"17.0\",\"lessThan\":\"27.3.4.17\",\"versionType\":\"otp\",\"status\":\"affected\"},{\"version\":\"28.0\",\"lessThan\":\"28.5.0.6\",\"versionType\":\"otp\",\"status\":\"affected\"},{\"version\":\"29.0\",\"lessThan\":\"29.0.6\",\"versionType\":\"otp\",\"status\":\"affected\"}]},{\"vendor\":\"Erlang\",\"product\":\"OTP\",\"defaultStatus\":\"unaffected\",\"packageName\":\"inets\",\"cpes\":[\"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\"],\"modules\":[\"mod_auth\",\"mod_alias\",\"httpd_request\"],\"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\",\"packageURL\":\"pkg:otp/inets\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"5.10\",\"versionType\":\"otp\",\"status\":\"unknown\"},{\"version\":\"5.10\",\"lessThan\":\"9.3.2.7\",\"versionType\":\"otp\",\"status\":\"affected\"},{\"version\":\"9.4\",\"lessThan\":\"9.6.2.3\",\"versionType\":\"otp\",\"status\":\"affected\"},{\"version\":\"9.7\",\"lessThan\":\"9.7.2\",\"versionType\":\"otp\",\"status\":\"affected\"}]},{\"vendor\":\"Erlang\",\"product\":\"OTP\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://github.com\",\"packageName\":\"erlang/otp\",\"cpes\":[\"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\"],\"modules\":[\"mod_auth\",\"mod_alias\",\"httpd_request\"],\"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\",\"packageURL\":\"pkg:github/erlang/otp\",\"versions\":[{\"version\":\"84adefa331c4159d432d22840663c38f155cd4c1\",\"lessThan\":\"*\",\"versionType\":\"git\",\"status\":\"affected\",\"changes\":[{\"at\":\"bac19eb3dbd96cc49b6d8cabc1c04248bf8c79f6\",\"status\":\"unaffected\"},{\"at\":\"d8878dec0ececc2eab18e47bb18b472f224ca633\",\"status\":\"unaffected\"},{\"at\":\"9641944a2efbf55bea760f8ff7ba777fe3a0961c\",\"status\":\"unaffected\"}]}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":8.2,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2026-09-01T17:57:48.578657Z\",\"id\":\"CVE-2026-66835\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"no\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-50\"}]}],\"references\":[{\"url\":\"https://cna.erlef.org/cves/CVE-2026-66835.html\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/erlang/otp/commit/9641944a2efbf55bea760f8ff7ba777fe3a0961c\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/erlang/otp/commit/bac19eb3dbd96cc49b6d8cabc1c04248bf8c79f6\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/erlang/otp/commit/d8878dec0ececc2eab18e47bb18b472f224ca633\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://github.com/erlang/otp/security/advisories/GHSA-r4vv-vc2c-2fw6\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://osv.dev/vulnerability/EEF-CVE-2026-66835\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"},{\"url\":\"https://www.erlang.org/doc/system/versions.html#order-of-versions\",\"source\":\"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\"}]}}",
"vulnrichment": {
"containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-66835\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-09-01T17:57:48.578657Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-09-01T17:58:07.499Z\"}}], \"cna\": {\"title\": \"httpd mod_auth directory protection bypassed by a doubled slash in the request path\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"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\"}], \"impacts\": [{\"capecId\": \"CAPEC-126\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-126 Path Traversal\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 8.2, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"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\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"HIGH\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"cpes\": [\"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\"], \"vendor\": \"Erlang\", \"modules\": [\"mod_auth\", \"mod_alias\", \"httpd_request\"], \"product\": \"OTP\", \"versions\": [{\"status\": \"unknown\", \"version\": \"0\", \"lessThan\": \"17.0\", \"versionType\": \"otp\"}, {\"status\": \"affected\", \"version\": \"17.0\", \"lessThan\": \"27.3.4.17\", \"versionType\": \"otp\"}, {\"status\": \"affected\", \"version\": \"28.0\", \"lessThan\": \"28.5.0.6\", \"versionType\": \"otp\"}, {\"status\": \"affected\", \"version\": \"29.0\", \"lessThan\": \"29.0.6\", \"versionType\": \"otp\"}], \"packageURL\": \"pkg:sid/erlang.org/otp\", \"packageName\": \"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\"], \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"mod_auth:secret_path/3\"}, {\"name\": \"mod_alias:real_name/3\"}, {\"name\": \"httpd_request:validate_uri/1\"}]}, {\"cpes\": [\"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/erlang/otp\", \"vendor\": \"Erlang\", \"modules\": [\"mod_auth\", \"mod_alias\", \"httpd_request\"], \"product\": \"OTP\", \"versions\": [{\"status\": \"unknown\", \"version\": \"0\", \"lessThan\": \"5.10\", \"versionType\": \"otp\"}, {\"status\": \"affected\", \"version\": \"5.10\", \"lessThan\": \"9.3.2.7\", \"versionType\": \"otp\"}, {\"status\": \"affected\", \"version\": \"9.4\", \"lessThan\": \"9.6.2.3\", \"versionType\": \"otp\"}, {\"status\": \"affected\", \"version\": \"9.7\", \"lessThan\": \"9.7.2\", \"versionType\": \"otp\"}], \"packageURL\": \"pkg:otp/inets\", \"packageName\": \"inets\", \"programFiles\": [\"src/http_server/mod_auth.erl\", \"src/http_server/mod_alias.erl\", \"src/http_server/httpd_request.erl\"], \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"mod_auth:secret_path/3\"}, {\"name\": \"mod_alias:real_name/3\"}, {\"name\": \"httpd_request:validate_uri/1\"}]}, {\"cpes\": [\"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/erlang/otp\", \"vendor\": \"Erlang\", \"modules\": [\"mod_auth\", \"mod_alias\", \"httpd_request\"], \"product\": \"OTP\", \"versions\": [{\"status\": \"affected\", \"changes\": [{\"at\": \"bac19eb3dbd96cc49b6d8cabc1c04248bf8c79f6\", \"status\": \"unaffected\"}, {\"at\": \"d8878dec0ececc2eab18e47bb18b472f224ca633\", \"status\": \"unaffected\"}, {\"at\": \"9641944a2efbf55bea760f8ff7ba777fe3a0961c\", \"status\": \"unaffected\"}], \"version\": \"84adefa331c4159d432d22840663c38f155cd4c1\", \"lessThan\": \"*\", \"versionType\": \"git\"}], \"packageURL\": \"pkg:github/erlang/otp\", \"packageName\": \"erlang/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\"], \"collectionURL\": \"https://github.com\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"mod_auth:secret_path/3\"}, {\"name\": \"mod_alias:real_name/3\"}, {\"name\": \"httpd_request:validate_uri/1\"}]}], \"references\": [{\"url\": \"https://github.com/erlang/otp/security/advisories/GHSA-r4vv-vc2c-2fw6\", \"tags\": [\"vendor-advisory\", \"related\"]}, {\"url\": \"https://cna.erlef.org/cves/CVE-2026-66835.html\", \"tags\": [\"related\"]}, {\"url\": \"https://osv.dev/vulnerability/EEF-CVE-2026-66835\", \"tags\": [\"related\"]}, {\"url\": \"https://www.erlang.org/doc/system/versions.html#order-of-versions\", \"tags\": [\"x_version-scheme\"]}, {\"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\", \"tags\": [\"patch\"]}], \"descriptions\": [{\"lang\": \"en\", \"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.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003ePath Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a \u003ccode\u003emod_auth\u003c/code\u003e protected directory by prefixing the request path with an extra slash.\u003c/p\u003e\\n\u003cp\u003e\u003ccode\u003ehttpd_request:validate_uri/1\u003c/code\u003e normalises the request URI with \u003ccode\u003euri_string:normalize/1\u003c/code\u003e, which performs RFC 3986 dot-segment removal but does not collapse empty path segments, so a doubled slash survives. \u003ccode\u003emod_alias:real_name/3\u003c/code\u003e concatenates the document root with that URI, and \u003ccode\u003emod_auth:secret_path/3\u003c/code\u003e then decides whether the result lies inside a protected \u003ccode\u003edirectory\u003c/code\u003e 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 \u003ccode\u003emod_get\u003c/code\u003e 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 \u003ccode\u003emod_security\u003c/code\u003e.\u003c/p\u003e\\n\u003cp\u003eThis issue affects OTP from OTP\u0026nbsp;17.0 before OTP\u0026nbsp;27.3.4.17, from OTP\u0026nbsp;28.0 before OTP\u0026nbsp;28.5.0.6, and from OTP\u0026nbsp;29.0 before OTP\u0026nbsp;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\u0026nbsp;17.0, corresponding to inets before 5.10, is affected is unknown.\u003c/p\u003e\", \"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.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-50\", \"description\": \"CWE-50 Path Equivalence: \u0027//multiple/leading/slash\u0027\"}]}], \"configurations\": [{\"lang\": \"en\", \"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.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eOnly servers that protect a directory with \u003ccode\u003emod_auth\u003c/code\u003e, by configuring a \u003ccode\u003edirectory\u003c/code\u003e block with authentication requirements, are affected. A server that serves no authenticated directory has no protection for this issue to bypass.\u003c/p\u003e\", \"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.\", \"base64\": false}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"27.3.4.17\"}, {\"criteria\": \"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"28.5.0.6\", \"versionStartIncluding\": \"28.0\"}, {\"criteria\": \"cpe:2.3:a:erlang:erlang\\\\/otp:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"29.0.6\", \"versionStartIncluding\": \"29.0\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-09-01T14:49:47.805Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-66835\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-09-01T17:58:31.739Z\", \"dateReserved\": \"2026-08-17T12:00:02.063Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-09-01T14:49:47.805Z\", \"assignerShortName\": \"EEF\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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