Path traversal in granian - #VU164384
Published: November 10, 2026
Vulnerability identifier: #VU164384
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-22
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to read server-readable files in sibling directories whose names share the configured static mount's path prefix.
The vulnerability exists due to path containment checks using string prefixes without path-component boundaries and permissive route matching in Granian's Windows static-file handling when processing requests with static serving enabled. A remote attacker can request /static-private/secret.txt, /static/../static-private/secret.txt, or /static/%2e%2e/static-private/secret.txt against a /static mount to disclose files from a prefix-sharing sibling directory.
Affected software
granian
Remediation
Install security update from vendor's website.
granian - update to 2.8.5