Spring SecurityFramework / library · VMware
CVE-2026-40988
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAn 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe spring-security-saml2-service-provider library contains an unbounded writer vulnerability when processing SAML 2.0 Login or Logout requests using the REDIRECT binding. Attackers can send specially crafted, inflated compressed SAML payloads that cause excessive memory consumption during decompression, leading to denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Spring SecurityFramework / library
>= 5.7.0, < 5.7.24>= 5.8.0, < 5.8.26>= 6.3.0, < 6.3.17>= 6.4.0, < 6.4.17>= 6.5.0, < 6.5.10.2>= 7.0.0, < 7.0.5.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Spring Security library versionInspect your project dependencies (pom.xml, build.gradle, or similar) for spring-security-saml2-service-provider or spring-security-version to determine the exact version in useAffected if The version falls within any of these ranges: >= 5.7.0 and < 5.7.24, >= 5.8.0 and < 5.8.26, >= 6.3.0 and < 6.3.17, >= 6.4.0 and < 6.4.17, >= 6.5.0 and < 6.5.11, or >= 7.0.0 and < 7.0.6
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Verify SAML 2.0 Login configurationLocate your Spring Security configuration class or XML file and search for SAML 2.0 login configuration, typically using .saml2Login() or SAML 2.0 related bean definitionsAffected if SAML 2.0 login is configured and the application uses spring-security-saml2-service-provider
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Confirm REDIRECT binding is in useIn your SAML configuration, check the binding type specified for login or logout requests. Look for configuration like .redirectBinding() or default REDIRECT binding behavior in the RelyingPartyRegistrationAffected if REDIRECT binding is explicitly configured or is the default binding for SAML 2.0 authentication flows in your environment
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Check for payload size limits at application edgeInspect any web server, API gateway, or load balancer in front of the application for request size limits, content-length restrictions, or SAML message validation that could mitigate large payload attacksAffected if No request size limits or SAML message validation exist at the edge and the application is directly exposed to unauthenticated SAML requests
You are affected if your environment uses a vulnerable Spring Security version (5.7.x before 5.7.24, 5.8.x before 5.8.26, 6.3.x before 6.3.17, 6.4.x before 6.4.17, 6.5.x before 6.5.11, or 7.0.x before 7.0.6) with SAML 2.0 Login/Logout configured using REDIRECT binding and no payload size restrictions exist upstream to limit compressed SAML message sizes.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped5.7.245.8.266.3.17
Upgrade Spring Security to a patched version beyond 5.7.23, 5.8.25, 6.3.16, 6.4.16, 6.5.10, or 7.0.5. If immediate upgrade is not possible, consider rate limiting or filtering SAML requests at the application gateway.
Spring Security 5.7.24 / 5.8.26 / 6.3.17 / 6.4.17 (or latest in your respective branch)
- 1. Identify the current Spring Security version in your project's dependency management (e.g., pom.xml, build.gradle)
- 2. Determine which major version branch you are using (5.7.x, 5.8.x, 6.3.x, 6.4.x, 6.5.x, or 7.0.x)
- 3. For Spring Security 5.7.x: upgrade to version 5.7.24 or later
- 4. For Spring Security 5.8.x: upgrade to version 5.8.26 or later
- 5. For Spring Security 6.3.x: upgrade to version 6.3.17 or later
- 6. For Spring Security 6.4.x: upgrade to version 6.4.17 or later
- 7. For Spring Security 6.5.x: upgrade to version 6.5.11 or later (if available)
- 8. For Spring Security 7.0.x: upgrade to version 7.0.6 or later (if available)
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Spring Security
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,096.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40988 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-40988 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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