CVE-2026-73270

Description

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
erlang	26.04 LTS resolute	Fixed 1:27.3.4.6+dfsg-1ubuntu0.1
	24.04 LTS noble	Fixed 1:25.3.2.8+dfsg-1ubuntu4.7
	22.04 LTS jammy	Fixed 1:24.2.1+dfsg-1ubuntu0.7
	20.04 LTS focal	Fixed 1:22.2.7+dfsg-1ubuntu0.5+esm2
	18.04 LTS bionic	Fixed 1:20.2.2+dfsg-1ubuntu2+esm3
	16.04 LTS xenial	Fixed 1:18.3-dfsg-1ubuntu3.1+esm3
	14.04 LTS trusty	Fixed 1:16.b.3-dfsg-1ubuntu2.2+esm2

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
erlang	Upstream: 9641944 Upstream: bac19eb Upstream: d8878de

Severity score breakdown

CVSS version: CVSS v4.0

Base score 8.2 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Attack requirements	Present
Privileges required	None
User interaction	None
Vulnerable system - Confidentiality impact	High
Vulnerable system - Integrity impact	None
Vulnerable system - Availability impact	None
Subsequent system - Confidentiality impact	None
Subsequent system - Integrity impact	None
Subsequent system - Availability impact	None

Scores

Parameter	Value
Base score	8.2 · High
Base + Threat score	-
Base + Environmental score	-
Base + Threat + Environmental score	-

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

References

Related Ubuntu Security Notices (USN)

USN-8827-1
Erlang vulnerabilities
28 September 2026

Other references

https://www.cve.org/CVERecord?id=CVE-2026-73270