Denial of Service in Spring Security SAML2-REDIRECT (5.7.07.0.5)
CVE-2026-40988 Published on June 9, 2026
Unbounded DEFLATE Inflation in SAML 2.0 Service Provider
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.
Vulnerability Analysis
CVE-2026-40988 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
What is a Resource Exhaustion Vulnerability?
The software does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
CVE-2026-40988 has been classified to as a Resource Exhaustion vulnerability or weakness.
Products Associated with CVE-2026-40988
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Affected Versions
Spring Security:- Version 5.7.0 and below 5.7.24 is affected.
- Version 5.8.0 and below 5.8.26 is affected.
- Version 6.3.0 and below 6.3.17 is affected.
- Version 6.4.0 and below 6.4.17 is affected.
- Version 6.5.0 and below 6.5.11 is affected.
- Version 7.0.0 and below 7.0.6 is affected.