---
title: "CVE-2026-87830: StAX WS-SecurityPolicy Validator - Broken Access Control"
description: "StAX streaming WS-SecurityPolicy validator contains a broken access control vulnerability caused by incorrect handling of relative or unsupported XPath expressions, letting remote SOAP peers bypass signature or encryption requirements, exploit requires sending crafted SOAP messages."
url: https://panop.io/threat-heartbeat/CVE-2026-87830/
---

# CVE-2026-87830 StAX WS-SecurityPolicy Validator - Broken Access Control

StAX streaming WS-SecurityPolicy validator contains a broken access control vulnerability caused by incorrect handling of relative or unsupported XPath expressions, letting remote SOAP peers bypass signature or encryption requirements, exploit requires sending crafted SOAP messages.

CVSS base score 9.1 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.21% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-87830)

## Details

Type

Broken Access Control

Impact

Broken Access Control

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Published

30 September 2026

Updated

15 October 2026

Weakness

[CWE-917](https://cwe.mitre.org/data/definitions/917.html)

## Vendor fix

Upgrade to versions 4.0.2, 3.0.6, or 2.4.4 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-87830](https://nvd.nist.gov/vuln/detail/CVE-2026-87830)
- [https://lists.apache.org/thread.html/lwlozb1x20d16f9dnyvoygc9rrhzq2vn](https://lists.apache.org/thread.html/lwlozb1x20d16f9dnyvoygc9rrhzq2vn)
- [http://www.openwall.com/lists/oss-security/2026/09/30/9](http://www.openwall.com/lists/oss-security/2026/09/30/9)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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