Path Equivalence: \'//multiple/leading/slash\' in Erlang OTP - CVE-2026-66835
Published: September 2, 2026
Vulnerability identifier: #VU146835
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-66835
CWE-ID: CWE-50
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose protected files.
The vulnerability exists due to path equivalence handling in inets httpd mod_auth directory protection when processing request paths with repeated leading slashes. A remote attacker can send a specially crafted request with an extra slash in the path to disclose protected files.
This requires an inets httpd deployment that enforces mod_auth on a directory block.
Affected software
Erlang OTP
How to mitigate CVE-2026-66835
Install security update from vendor's website.
Erlang OTP - addressed in versions 17.0, 27.3.4.17, 28.5.0.6, 29.0.6