Vulnerability in Bastillion-Io Bastillion
CVE-2026-75627
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.008 (56.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.008 · change: +0.004
Affected products
Weakness classification (CWE)
References
- github.com/bastillion-io/Bastillion/issues/669 (issue-tracking)
- github.com/bastillion-io/Bastillion (product)
- github.com/bastillion-io/Bastillion/commit/d759fb686a1a097b1b026e286fd9b20e5ba3… (patch)
- github.com/bastillion-io/Bastillion/blob/master/src/main/java/loophole/mvc/base… (technical-description)
- www.vulncheck.com/advisories/bastillion-authentication-bypass-via-path-prefix-r… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-75627?
- CVE-2026-75627 is a critical-severity vulnerability in Bastillion-Io Bastillion, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 9.8/10. Published 2026-08-18.
- How severe is CVE-2026-75627?
- Critical severity. CVSS v3 base score is 9.8 out of 10.