Unbounded DEFLATE Inflation in SAML 2.0 Service Provider
CVE-2026-40988

7.5HIGH

Key Information:

Vendor

Spring

Status
Spring Security
Vendor
CVE Published:
9 June 2026

What is CVE-2026-40988?

An application using spring-security-saml2-service-provider and the REDIRECT binding for SAML 2.0 Login or Logout may be vulnerable to a denial of service by way of an unbounded writer that inflates the compressed SAML payload into memory.

Affected versions: Spring Security 5.7.0 through 5.7.23; 5.8.0 through 5.8.25; 6.3.0 through 6.3.16; 6.4.0 through 6.4.16; 6.5.0 through 6.5.10; 7.0.0 through 7.0.5.

Affected Version(s)

Spring Security 5.7.0 < 5.7.24

Spring Security 5.8.0 < 5.8.26

Spring Security 6.3.0 < 6.3.17

References

https://spring.io/security/cve-2026-40988

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.