# CVE-2026-73857: ModSecurity uninitialized pointer dereference in XML parsing

Source: https://junglewise.ai/threats/cve-2026-73857-modsecurity-is-an-open-source-cross-platform-web-application  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-09. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-73857 · Severity: high · CVSS 7.5 · Published 2026-11-09

ModSecurity is a web application firewall that protects web servers by filtering malicious traffic. Versions 3.0.15 through 3.0.16 contain a flaw in XML request processing that can be triggered by a single crafted HTTP request, causing the firewall process to crash, leak sensitive memory contents, or potentially execute attacker-controlled code.

Technologies: [OWASP Modsecurity](https://junglewise.ai/threats/technologies/modsecurity). Vendors: [OWASP](https://junglewise.ai/threats/vendors/owasp).

## Quick answers

**Is CVE-2026-73857 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-73857 being exploited in the wild.

**How severe is CVE-2026-73857?** High severity, with a CVSS score of 7.5, published 9 November 2026.

**Which products and versions are affected?** OWASP Modsecurity 3.0.15 to 3.0.16.

**Is there a fix for CVE-2026-73857?** Yes: fixed in 3.0.17. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-73857 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-73857?** Check whether you run OWASP Modsecurity at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 3.0.17

## Technical details

An uninitialized pointer dereference exists in the SAX end-element callback of XML request body processing when SecParseXmlIntoArgs is enabled (On or OnlyArgs). An unauthenticated attacker can send a crafted XML HTTP request that dereferences an uninitialized pointer, writing a constant value to an attacker-controlled memory address. This memory corruption can crash the worker process, disclose memory contents, or redirect execution flow.

## Affected products

- OWASP ModSecurity 3.0.15 to 3.0.16

## Timeline

- 2026-11-09: disclosed

## References

- [https://github.com/owasp-modsecurity/ModSecurity/commit/e979a73e89d60cefdf42b41bb38bf1e456d7909f](https://github.com/owasp-modsecurity/ModSecurity/commit/e979a73e89d60cefdf42b41bb38bf1e456d7909f)
- [https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17](https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17)

## Related threats

- [ModSecurity htmlEntityDecode rule bypass via incomplete entity handling](https://junglewise.ai/threats/cve-2026-61812-modsecurity-is-an-open-source-cross-platform-web-application)
- [ModSecurity removeComments bypass via adjacent comments](https://junglewise.ai/threats/cve-2026-104259-modsecurity-is-an-open-source-cross-platform-web-application)
- [ModSecurity response body inspection bypass with mixed-case Content-Type](https://junglewise.ai/threats/cve-2026-73856-modsecurity-is-an-open-source-cross-platform-web-application)
- [ModSecurity multipart parser filename precedence bypass](https://junglewise.ai/threats/cve-2026-104269-modsecurity-is-an-open-source-cross-platform-web-application)
- [ModSecurity @rxGlobal match-limit bypass](https://junglewise.ai/threats/cve-2026-103932-modsecurity-is-an-open-source-cross-platform-web-application)