GHSA-27xw-p8v6-9jjr: org.springframework.security:spring-security-core (CVE-2018-15801)

Package	Ecosystem	Affected	Fixed in
org.springframework.security:spring-security-core	Maven	>=5.1.0, <5.1.2	5.1.2
org.springframework.security:spring-security-oauth2-jose	Maven	>=5.1.0, <5.1.2	5.1.2

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Spring Security 5.1.0 through 5.1.1 (spring-security-core and spring-security-oauth2-jose) contains an authorization bypass in JWT issuer validation. An attacker can exploit this only when the same private key is used to sign JWTs for both an honest issuer and a malicious user; the attacker could then craft signed JWTs with a malicious issuer URL that may be granted access as the honest issuer. Upgrade to 5.1.2 or later.

Written 8 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
3.3	Low	3.0	CVSS:3.0/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N	CNA (dell)

CISA KEV Not listed.
EPSS 0.0065, the 51st percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 15:13 UTC First seen by agentprime
31 Oct 2026, 15:13 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.