CVE-2026-66835
published 2026-09-01CVE-2026-66835: Path Equivalence vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a mod_auth protected directory by…
PriorityP356high8.2CVSS 4.0
AVNACLATPPRNUINVCHVINVANSCNSINSANEXCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUX
EPSS
0.97%
61.7th percentile
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
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| erlang | otp | >= 17.0 < 27.3.4.17 | 27.3.4.17 |
| erlang | otp | >= 28.0 < 28.5.0.6 | 28.5.0.6 |
| erlang | otp | >= 29.0 < 29.0.6 | 29.0.6 |
| erlang | otp | >= 5.10 < 9.3.2.7 | 9.3.2.7 |
| erlang | otp | >= 84adefa331c4159d432d22840663c38f155cd4c1 < * | * |
| erlang | otp | >= 9.4 < 9.6.2.3 | 9.6.2.3 |
| erlang | otp | >= 9.7 < 9.7.2 | 9.7.2 |
| ubuntu | erlang | — | — |
CVSS provenance
nvdv4.08.2HIGHCVSS: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
vendor_redhat8.2HIGH
vendor_ubuntu7.5HIGH
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VulDB
Erlang OTP httpd httpd_request:validate_uri path traversal (EUVD-2026-69245 / WID-SEC-2026-3146)
vuldb·2026-09-03·CVSS 8.2
CVE-2026-66835 [HIGH] Erlang OTP httpd httpd_request:validate_uri path traversal (EUVD-2026-69245 / WID-SEC-2026-3146)
A vulnerability described as problematic has been identified in Erlang OTP. This affects the function httpd_request:validate_uri of the component httpd. Executing a manipulation can lead to path traversal.
This vulnerability is handled as CVE-2026-66835. The attack can be executed remotely. There is not any exploit available.
Ubuntu
Erlang vulnerabilities
vendor_ubuntu·2026-09-28·CVSS 7.5
CVE-2026-23941 [HIGH] Erlang vulnerabilities
Title: Erlang vulnerabilities
Summary: Several security issues were fixed in Erlang.
It was discovered that the Erlang Port Mapper Daemon did not properly
handle slow connections. A remote attacker could possibly use this issue
to cause a denial of service. (CVE-2026-42792)
It was discovered that Erlang incorrectly handled certain external term
format data, leading to heap corruption. An attacker could possibly use
this issue to cause Erlang to crash, resulting in a denial of service.
This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS.
(CVE-2026-55737)
It was discovered that Erlang incorrectly handled invalid external term
format data. An attacker could possibly use this issue to cause Erlang to
crash, resulting in a denial of service. This issue only affected Ubuntu
26.04
Red Hat
inets: Erlang/OTP inets httpd: Directory protection bypass allows information disclosure
vendor_redhat·2026-09-01·CVSS 8.2
CVE-2026-66835 [HIGH] CWE-41 inets: Erlang/OTP inets httpd: Directory protection bypass allows information disclosure
inets: Erlang/OTP inets httpd: Directory protection bypass allows information disclosure
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 th
No detection rules found.
No public exploits indexed.
https://cna.erlef.org/cves/CVE-2026-66835.htmlhttps://github.com/erlang/otp/commit/9641944a2efbf55bea760f8ff7ba777fe3a0961chttps://github.com/erlang/otp/commit/bac19eb3dbd96cc49b6d8cabc1c04248bf8c79f6https://github.com/erlang/otp/commit/d8878dec0ececc2eab18e47bb18b472f224ca633https://github.com/erlang/otp/security/advisories/GHSA-r4vv-vc2c-2fw6https://osv.dev/vulnerability/EEF-CVE-2026-66835https://www.erlang.org/doc/system/versions.html#order-of-versions
2026-09-01
Published