> CVE-2026-66835 [HIGH]

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PUBLISHED
2026-09-01 15:17
MODIFIED
2026-09-01 15:17
CVSS_SCORE V3
8.2
EPSS (Prob. Exploit)
0.97%
Top 38.3%
DATA SOURCES:
NVD đź”— 2026-09-01 CWE MITRE đź”— 2026-10-01 FIRST EPSS đź”— 2026-10-25 OSV đź”— 2026-09-07 MSRC đź”— 2026-09-07

> DESCRIPTION

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.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
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

> MÉTRIQUES CVSS DÉTAILLÉES

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
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
High (H)
Divulgation totale d'informations
I (Impact Intégrité)
Integrity Impact
None (N)
Aucune modification de données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

Confidentialité
High
Divulgation totale d'informations
Intégrité
None
Aucune modification de données possible
Disponibilité
None
Aucune interruption de service

> WEAKNESSES

CWE-50

> CWE DETAILED DESCRIPTIONS

CWE-50: Path Equivalence: '//multiple/leading/slash' - The product accepts path input in the form of multiple leading slash ('//multiple/leading/slash') without appropriate validation, which can lead to ambiguous path resolution and allow an attacker to traverse the file system to unintended locations or access arbitrary files.

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

httpd mod_auth directory protection bypassed by a doubled slash in the request path

AFFECTED PACKAGES:
Unknown / Unknown
88 versions affected
ALIASES:
EEF-CVE-2026-66835, GHSA-r4vv-vc2c-2fw6

> HISTORIQUE DES MODIFICATIONS

Première apparition
01/09/2026 15:17
Source: NVD
📊 ENRICHISSEMENT 01/10/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-50: Path Equivalence: '//multiple/leading/slash' - The product accepts path input in the form of multiple leading slash ('//multiple/leading/slash') without appropriate validation, which can lead ...
Total des modifications: 1 Dernière mise à jour: 4 weeks ago

> REFERENCES

https://cna.erlef.org/cves/CVE-2026-66835.html
https://github.com/erlang/otp/commit/9641944a2efbf55bea760f8ff7ba777fe3a0961c
https://github.com/erlang/otp/commit/bac19eb3dbd96cc49b6d8cabc1c04248bf8c79f6
https://github.com/erlang/otp/commit/d8878dec0ececc2eab18e47bb18b472f224ca633
https://github.com/erlang/otp/security/advisories/GHSA-r4vv-vc2c-2fw6
https://osv.dev/vulnerability/EEF-CVE-2026-66835
https://www.erlang.org/doc/system/versions.html#order-of-versions
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