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PatchSiren cyber security CVE debrief

CVE-2026-40988 Spring CVE debrief

CVE-2026-40988 is a HIGH severity vulnerability in Spring Security that can lead to a denial of service via an unbounded writer that inflates the compressed SAML payload into memory. The vulnerability affects Spring Security versions 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, and 7.0.0 through 7.0.5.

Vendor
Spring
Product
Spring Security
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-10
Original CVE updated
2026-07-17
Advisory published
2026-06-10
Advisory updated
2026-07-17

Who should care

Users of affected Spring Security versions should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by an unbounded writer that inflates the compressed SAML payload into memory when using the REDIRECT binding for SAML 2.0 Login or Logout. This can lead to a denial of service.

Defensive priority

HIGH

Recommended defensive actions

  • Upgrade to a non-vulnerable version of Spring Security.
  • Apply patches or updates provided by the vendor.
  • Implement additional security measures to prevent similar attacks.

Evidence notes

The CVE record and NVD detail pages provide additional information about the vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-40988 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-40988

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-40988 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-40988

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.