CVE-2026-40988 | 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.

Published: 2026-06-10 Last update: 2026-06-12 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-40988 is rated Low Risk (38.7/100): CVSS High severity, with low exploitation likelihood (EPSS 0.32%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-40988

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.04% 0.32% +0.28%
2 2026-06-10 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-40988

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-40988

GitHub Security Advisory for CVE-2026-40988

GHSA-m69x-pw9p-7j3q · Severity: high — An application using spring-security-saml2-service-provider and the REDIRECT binding for SAML 2.0...

Affected software / configurations for CVE-2026-40988

Vendor Product Version Raw CPE
vmware spring_security >= 5.7.0, < 5.7.24 cpe:2.3:a:vmware:spring_security:*:*:*:*:*:*:*:*
vmware spring_security >= 5.8.0, < 5.8.26 cpe:2.3:a:vmware:spring_security:*:*:*:*:*:*:*:*
vmware spring_security >= 6.3.0, < 6.3.17 cpe:2.3:a:vmware:spring_security:*:*:*:*:*:*:*:*
vmware spring_security >= 6.4.0, < 6.4.17 cpe:2.3:a:vmware:spring_security:*:*:*:*:*:*:*:*
vmware spring_security >= 6.5.0, < 6.5.11 cpe:2.3:a:vmware:spring_security:*:*:*:*:*:*:*:*
vmware spring_security >= 7.0.0, < 7.0.6 cpe:2.3:a:vmware:spring_security:*:*:*:*:*:*:*:*

References for CVE-2026-40988

cvelogic Threat Intelligence