CVE-2026-40988
HIGHCVE-2026-40988 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in org.springframework.security:spring-security-saml2-service-provider. O3 Security confirms whether CVE-2026-40988 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Unbounded DEFLATE Inflation in SAML 2.0 Service Provider
Real-World Exposure
org.springframework.security:spring-security-saml2-service-provider☕org.springframework.security:spring-security-saml2-service-provider☕org.springframework.security:spring-security-saml2-service-provider☕org.springframework.security:spring-security-saml2-service-provider☕org.springframework.security:spring-security-saml2-service-provider☕org.springframework.security:spring-security-saml2-service-providerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.springframework.security:spring-security-saml2-service-provider | ≥ 7.0.0&&< 7.0.6 | 7.0.6 |
| ☕Maven | org.springframework.security:spring-security-saml2-service-provider | ≥ 6.5.0&&< 6.5.11 | 6.5.11 |
| ☕Maven | org.springframework.security:spring-security-saml2-service-provider | ≥ 6.4.0 | No fix |
| ☕Maven | org.springframework.security:spring-security-saml2-service-provider | ≥ 6.3.0 | No fix |
| ☕Maven | org.springframework.security:spring-security-saml2-service-provider | ≥ 5.8.0 | No fix |
| ☕Maven | org.springframework.security:spring-security-saml2-service-provider | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.springframework.security:spring-security-saml2-service-provider. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.springframework.security:spring-security-saml2-service-provider to 7.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40988 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-40988 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-40988. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-40988 in your dependencies?
O3 detects CVE-2026-40988 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.