CVE-2026-40988

Unbounded DEFLATE Inflation in SAML 2.0 Service Provider

HIGH

7.5

CVSS Score

Published: June 9, 2026 at 11:46 PM UTC

Updated: July 23, 2026 at 07:32 PM UTC

2 products affected across 2 vendorsSpring SecuritySpring Security

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Severity

HIGH7.5

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Spring Security · VMware

95%

5.7.0 ≤ v < 5.7.245.8.0 ≤ v < 5.8.266.3.0 ≤ v < 6.3.176.4.0 ≤ v < 6.4.176.5.0 ≤ v < 6.5.10.27.0.0 ≤ v < 7.0.5.1

Affected range stops below 5.7.24, so it looks safe — our inference, not a vendor statement

Affected range stops below 5.8.26, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.3.17, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.4.17, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.5.10.2, so it looks safe — our inference, not a vendor statement

Affected range stops below 7.0.5.1, so it looks safe — our inference, not a vendor statement

Spring Security · Spring

60%

5.7.0 ≤ v < 5.7.245.8.0 ≤ v < 5.8.266.3.0 ≤ v < 6.3.176.4.0 ≤ v < 6.4.176.5.0 ≤ v < 6.5.10.27.0.0 ≤ v < 7.0.5.15.7.0 5.8.0 6.3.0 6.4.0 6.5.0 7.0.0

Affected range stops below 5.7.24, so it looks safe — our inference, not a vendor statement

Affected range stops below 5.8.26, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.3.17, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.4.17, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.5.10.2, so it looks safe — our inference, not a vendor statement

Affected range stops below 7.0.5.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

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

References (1)

Vendor Advisory

Source: cverecord

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

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHvmware

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-400

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