CVE-2026-40189: goshs has a file-based ACL authorization bypass in goshs state-changing routes

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-10 · updated 2026-10-26
Weakness: CWE-862

Description

goshs is a SimpleHTTPServer written in Go. Prior to 2.0.0-beta.4, goshs enforces the documented per-folder .goshs ACL/basic-auth mechanism for directory listings and file reads, but it does not enforce the same authorization checks for state-changing routes. An unauthenticated attacker can upload files with PUT, upload files with multipart POST /upload, create directories with ?mkdir, and delete files with ?delete inside a .goshs-protected directory. By deleting the .goshs file itself, the attacker can remove the folder's auth policy and then access previously protected content without credentials. This results in a critical authorization bypass affecting confidentiality, integrity, and availability. This vulnerability is fixed in 2.0.0-beta.4.

Affected products

patrickhener goshs: before 2.0.0; 2.0.0-beta1, 2.0.0-beta2, 2.0.0-beta3 — fixed in 2.0.0

How to fix

Upgrade to a fixed version: patrickhener goshs 2.0.0. Check the vendor advisory for mitigations.

References

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