CVE-2026-40996
MEDIUMCVE-2026-40996 is a medium-severity (CVSS 4.8) Broken Cryptographic Algorithm vulnerability in org.springframework.ws:spring-ws-security. O3 Security confirms whether CVE-2026-40996 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Spring Web Services: Inbound WS-Security allows RSA PKCS#1 v1.5 key transport by default
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-40996.
Real-World Exposure
org.springframework.ws:spring-ws-security☕org.springframework.ws:spring-ws-security☕org.springframework.ws:spring-ws-security☕org.springframework.ws:spring-ws-securityReal-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
Wss4jSecurityInterceptor defaulted allowRSA15KeyTransportAlgorithm to true, overriding Apache WSS4J's safer default for validation RequestData. Inbound WS-Security decryption could therefore accept RSA PKCS#1 v1.5 (rsa-1_5) encrypted key material unless operators explicitly reconfigured the flag.
Affected versions: Spring Web Services 5.0.0 through 5.0.1; 4.1.0 through 4.1.3; 4.0.0 through 4.0.18; 3.1.0 through 3.1.8.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.springframework.ws:spring-ws-security | ≥ 5.0.0&&< 5.0.2 | 5.0.2 |
| ☕Maven | org.springframework.ws:spring-ws-security | ≥ 4.1.0&&< 4.1.4 | 4.1.4 |
| ☕Maven | org.springframework.ws:spring-ws-security | ≥ 4.0.0 | No fix |
| ☕Maven | org.springframework.ws:spring-ws-security | ≥ 3.1.0 | 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.ws:spring-ws-security. 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.ws:spring-ws-security to 5.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40996 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-2026-40996 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-2026-40996. 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-2026-40996 in your dependencies?
O3 detects CVE-2026-40996 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.