# CVE-2026-73857: ModSecurity v3 XML Request Body Processor Uninitialized Pointer Dereference Vulnerability

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.15 until 3.0.17, XML request body processing with SecParseXmlIntoArgs set to On or OnlyArgs can leave XMLNodes::parsing_ctx_arg uninitialized in the SAX end-element callback. A single crafted unauthenticated HTTP request can make a worker dereference the pointer, resulting in a constant-value write to an attacker-controlled address. The resulting memory corruption can terminate the worker and may disclose memory or redirect execution. Earlier 3.0.x releases and ModSecurity 2.x do not use the affected path. This issue is fixed in version 3.0.17.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- owasp-modsecurity / ModSecurity: >= 3.0.15, < 3.0.17 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-787, CWE-824

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-jx3r-phvx-2jmj (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/owasp-modsecurity/ModSecurity/commit/e979a73e89d60cefdf42b41bb38bf1e456d7909f (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-73857; retrieved 2026-11-09; source updated 2026-11-09

Revision: 9e99ed5f35bc78695268034ee79479002db50667b27f4d0066fce6a3a99f0956

Canonical: https://y2.dev/cve/CVE-2026-73857

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