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Fencer Vulns
high 8.2

CVE-2026-73270 json

httpd mod_auth directory protection bypassed by request path casing on case-insensitive filesystems

published 2026-09-01 2 mo ago modified 2026-09-08 2 mo ago also EUVD-2026-69243

cvss
8.2
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

Improper Handling of Case Sensitivity vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a mod_auth protected directory by requesting them with different casing, on deployments whose filesystem is case-insensitive.

mod_auth:secret_path/3 decides whether a resolved filesystem path lies inside a protected directory block by running the configured directory path through re:run/3 without the caseless option. A request for /secret/file against a directory configured as /Secret therefore does not match, so the request is treated as unprotected and no authentication challenge is issued, while the filesystem resolves the differently cased path to the same file and mod_get serves it. Deployments on case-sensitive filesystems are unaffected, because there the filesystem itself rejects the mismatched casing.

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.

Patch / fix

  • Erlang OTP 9.3.2.7, 9.6.2.3, 9.7.2, 27.3.4.17, 28.5.0.6, 29.0.6
  • erlang Debian 13 1:27.3.4.1+dfsg-1+deb13u4
  • erlang Debian 14 1:29.0.6+dfsg-1

debian advisories DEBIAN-CVE-2026-73270

  • erlang Ubuntu 22.04 LTS 1:24.2.1+dfsg-1ubuntu0.7
  • erlang Ubuntu 24.04 LTS 1:25.3.2.8+dfsg-1ubuntu4.7
  • erlang Ubuntu 26.04 LTS 1:27.3.4.6+dfsg-1ubuntu0.1
  • erlang Ubuntu Pro 14.04 LTS 1:16.b.3-dfsg-1ubuntu2.2+esm2
  • erlang Ubuntu Pro 16.04 LTS 1:18.3-dfsg-1ubuntu3.1+esm3
  • erlang Ubuntu Pro 18.04 LTS 1:20.2.2+dfsg-1ubuntu2+esm3
  • erlang Ubuntu Pro 20.04 LTS 1:22.2.7+dfsg-1ubuntu0.5+esm2

ubuntu advisories UBUNTU-CVE-2026-73270

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • erlang27 hummingbird 1 27.3.4.17-0.1.hum1
  • erlang27-et hummingbird 1 27.3.4.17-0.1.hum1
  • erlang27-wx hummingbird 1 27.3.4.17-0.1.hum1
  • erlang27-ftp hummingbird 1 27.3.4.17-0.1.hum1
  • erlang27-ssh hummingbird 1 27.3.4.17-0.1.hum1
  • erlang27-ssl hummingbird 1 27.3.4.17-0.1.hum1
  • erlang27-asn1 hummingbird 1 27.3.4.17-0.1.hum1
  • erlang27-edoc hummingbird 1 27.3.4.17-0.1.hum1

red hat advisories RHSA-2026:62531

  • erlang Azure Linux 3.0 26.2.5.21-6

azure linux advisories AZL-98484

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-73270 updated cvss 7.5

erlang: inets: Erlang/OTP inets httpd: Information disclosure via case-insensitive path bypass

  • Red Hat OpenStack Platform 13 (Queens) erlang, erlang-ic, erlang-ftp, erlang-ose, erlang-ssh, erlang-ssl, +36 more Red Hat OpenStack Platform 16.2 erlang, erlang-ssl, erlang-asn1, erlang-erts, erlang-hipe, erlang-sasl, +15 more Red Hat OpenStack Platform 17.1 erlang, erlang-ssl, erlang-asn1, erlang-erts, erlang-sasl, erlang-snmp, +14 more Red Hat OpenStack Platform 18.0 erlang
    affected: no fix available
  • Red Hat Hardened Images erlang27 27.3.4.17-0.1.hum1, erlang27-et 27.3.4.17-0.1.hum1, erlang27-wx 27.3.4.17-0.1.hum1, erlang27-ftp 27.3.4.17-0.1.hum1, erlang27-ssh 27.3.4.17-0.1.hum1, erlang27-ssl 27.3.4.17-0.1.hum1, +33 more
    fixed: vendor fix RHSA-2026:62531

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.93% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.2 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
CNA 4.0 8.2 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

Affected products

  • Erlang OTP

Classification

Weakness
  • CWE-178 Improper Handling of Case Sensitivity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.