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Erlang OTP inets CVE-2026-66835

| EUVDEUVD-2026-69245 HIGH
Path Equivalence: '//multiple/leading/slash' (CWE-50)
2026-09-01 EEF
Information Disclosure Otp Erlang
8.2
CVSS 4.0 · Vendor: EEF
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Severity by source

Vendor (EEF) PRIMARY
8.2 HIGH
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
vuln.today AI
7.5 HIGH

Network-reachable with no credentials required per PR:N in input vector; high confidentiality only, no integrity or availability impact, scope unchanged.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
SUSE
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from Vendor (EEF).

CVSS VectorVendor: EEF

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

4
POC Analysis Generated
Sep 10, 2026 - 11:26 vuln.today
Source Code Evidence Fetched
Sep 01, 2026 - 15:28 vuln.today
Analysis Generated
Sep 01, 2026 - 15:28 vuln.today
CVE Published
Sep 01, 2026 - 14:49 cve.org
HIGH 8.2

DescriptionCVE.org

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.

AnalysisAI

Authentication bypass in Erlang/OTP inets httpd allows remote unauthenticated attackers to read files inside mod_auth-protected directories across OTP 17.0 through 29.0 by prefixing the request URI with an extra slash. The inets URI normalizer preserves doubled slashes that RFC 3986 dot-segment removal does not collapse, causing mod_auth's directory-protection regex to silently fail to match while the OS transparently serves the protected file. …

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Vulnerability AssessmentAI

Exploitation Exploitation requires that the target runs Erlang/OTP's inets httpd with at least one mod_auth directory-protection block explicitly defined in the httpd configuration. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 base score of 8.2 reflects a network-accessible (AV:N), low-complexity (AC:L), unauthenticated (PR:N), no-interaction (UI:N) attack producing high confidentiality impact (VC:H) with no integrity or availability loss. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Vendor-released patches are available: upgrade to OTP 27.3.4.17 or later (inets 9.3.2.7+) for the OTP-27 branch, OTP 28.5.0.6 or later (inets 9.6.2.3+) for the OTP-28 branch, or OTP 29.0.6 or later (inets 9.7.2+) for OTP-29, per the advisory at https://github.com/erlang/otp/security/advisories/GHSA-r4vv-vc2c-2fw6 and upstream commits bac19eb3, d8878dec, and 9641944a. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours, identify all systems running Erlang/OTP versions 17.0 through 29.0 and determine which have mod_auth configured for directory protection. …

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected

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CVE-2026-66835 vulnerability details – vuln.today
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