Vulnerability details

CVE-2026-75627

bastillion-io Bastillion

Bastillion Authentication Bypass via Path-Prefix Routing Mismatch

CVSS 4.0

9.3Critical

Official description

Bastillion fails to properly validate request URI paths in its controller dispatcher, allowing unauthenticated attackers to bypass authentication filters by prefixing requests with arbitrary path segments. Attackers can access administrative controllers to read user listings, create manager accounts, and register managed systems, gaining control over SSH access to the managed fleet.

CVSS scores

Score	Version	Source	Vector
9.3Critical	4.0	CVEProject cvelistV5 (CNA) (VulnCheck)	`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`
9.8Critical	3.1	CVEProject cvelistV5 (CNA) (VulnCheck)	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

Affected products

Vendor	Product	Versions	Source
bastillion-io	Bastillion	v ≤ 5.1.0	CVEProject cvelistV5 (CNA)

References and advisories

https://github.com/bastillion-io/Bastillion product
https://github.com/bastillion-io/Bastillion/commit/d759fb686a1a097b1b026e286fd9b20e5ba349c8 patch
https://github.com/bastillion-io/Bastillion/blob/master/src/main/java/loophole/mvc/base/BaseKontroller.java technical-description
https://www.vulncheck.com/advisories/bastillion-authentication-bypass-via-path-prefix-routing-mismatch third-party-advisory
https://github.com/bastillion-io/Bastillion/issues/669 issue-tracking

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Details

Published: 2026-08-18
Last updated: 2026-09-24
State: Published
Assigner (CNA): VulnCheck

Exploit prediction (EPSS)

0.84%

Probability of exploitation in 30 days

58.1%

Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable: Yes
Exploitation: Proof of concept
Technical impact: Total

Weaknesses (CWE)

CWE-288
Authentication Bypass Using an Alternate Path or Channel