CVE-2026-87830
CRITICAL 9.1In the StAX streaming WS-SecurityPolicy validator, certain relative or unsupported XPath expressions can be converted into paths that never match the actual XML element path. A remote SOAP peer may therefore send a required element without the expected signature or encryption. Users are recommended to upgrade to versions 4.0.2 or 3.0.6 or 2.4.4, which fix this issue.
Severe if exploited (CVSS 9.1), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.2%chance of exploitation in 30 days · 11th percentile
Impact if exploited
9.1CVSS 3.1 · CRITICAL
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-87830/poc.jsonMachine-readable PoC index for this CVE (for automation).Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-87830/poc.json
Weakness (CWE)
- CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Apache | Wss4j | < 2.4.4 |
| Apache | Wss4j | ≥ 3.0.0 and < 3.0.6 |
| Apache | Wss4j | ≥ 4.0.0 and < 4.0.2 |
All CVSS metrics
- CRITICAL 9.1 v3.1 · ADP Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - CRITICAL 9.1 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N