High severity · published Jun 9, 2026
CVE-2026-40988
Unbounded DEFLATE Inflation in SAML 2.0 Service Provider
7.5
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 26% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SS
Spring Security · Spring
5.7.0 before 5.7.24; 5.8.0 before 5.8.26; 6.3.0 before 6.3.17; 6.4.0 before 6.4.17; 6.5.0 before 6.5.10.2; 7.0.0 before 7.0.5.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40988
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-40988
Vendor Advisory
https://spring.io/security/cve-2026-40988
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