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PatchSiren cyber security CVE debrief

CVE-2026-40996 Spring CVE debrief

CVE-2026-40996 is a vulnerability in Spring Web Services that affects versions 5.0.0 through 5.0.1, 4.1.0 through 4.1.3, 4.0.0 through 4.0.18, and 3.1.0 through 3.1.8. The vulnerability arises from the Wss4jSecurityInterceptor's default setting of allowRSA15KeyTransportAlgorithm to true, which overrides Apache WSS4J's safer default. This allows for the acceptance of RSA PKCS#1 v1.5 (rsa-1_5) encrypted key material for inbound WS-Security decryption, unless explicitly reconfigured by operators.

Vendor
Spring
Product
Spring Web Services
CVSS
MEDIUM 4.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-11
Original CVE updated
2026-09-04
Advisory published
2026-06-11
Advisory updated
2026-09-04

Who should care

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

Technical summary

The vulnerability has a CVSS score of 4.8 and is classified as MEDIUM severity. It can be exploited through network-based attacks with high complexity and no user interaction.

Defensive priority

MEDIUM

Recommended defensive actions

  • Upgrade to a non-affected version of Spring Web Services.
  • Reconfigure the allowRSA15KeyTransportAlgorithm flag to false if upgrading is not feasible.

Evidence notes

The CVE record and NVD detail can be found at [cve-org] and [nvd], respectively. Additional information is available at [ref-4].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-40996 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-40996

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

  • CVE-2026-40996 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-40996

    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.