Auth bypass in Springblade
CVE-2026-56100
SpringBlade versions from 2.7.3 up to but not including 5.0.0 contain a privilege escalation vulnerability that allows authenticated attackers to create system administrator accounts by sending crafted POST requests to an unprotected internal Feign user-creation endpoint exposed via @RestController without authorization checks. Attackers can exploit the gateway's authentication filter, which only validates JWT parsing without verifying user roles or caller identity, and leverage a hardcoded JWT signing key embedded in publicly available JARs to forge tokens and escalate privileges from a low-privilege user to administrator, enabling cross-tenant data pollution and persistent backdoor access.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.005 (42.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 42.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
References
- Researcher Disclosure (technical-description, exploit)
- github.com/chillzhuang/SpringBlade/releases
- Patch Commit (patch)
- SpringBlade GitHub Repository (product)
- www.vulncheck.com/advisories/springblade-privilege-escalation-via-exposed-feign… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-56100?
- CVE-2026-56100 is a high-severity vulnerability in Springblade, classified under Missing Authorization. CVSS score: 8.1/10. Published 2026-08-28.
- How severe is CVE-2026-56100?
- High severity. CVSS v3 base score is 8.1 out of 10.