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Fencer Vulns
high 7.5

CVE-2026-40988 json

Unbounded DEFLATE Inflation in SAML 2.0 Service Provider

published 2026-06-09 5 mo ago modified 2026-08-12 2 mo ago also GHSA-m69x-pw9p-7j3q , EUVD-2026-35883

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.springframework.security:spring-security-saml2-service-provider 6.5.11, 7.0.6
  • Spring Spring Security 5.7.24, 5.8.26, 6.3.17, 6.4.17, 6.5.10.2, 7.0.5.1

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven org.springframework.security:spring-security-saml2-service-provider
>=7.0.0, <7.0.6
>=6.5.0, <6.5.11
>=6.4.0, <=6.4.16
>=6.3.0, <=6.3.16
>=5.8.0, <=5.8.25
<=5.7.23
7.0.6
6.5.11

Affected products

  • Spring Spring Security

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.