Is CVE-2026-30923 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-30923 being exploited in the wild.

How severe is CVE-2026-30923?

High severity, with a CVSS score of 7.5, published 5 May 2026.

Which products and versions are affected?

OWASP Libmodsecurity3 < 3.0.15.

Is there a fix for CVE-2026-30923?

A patch was published on 2026-04-28: Version 3.0.15 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-30923 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-30923?

Check whether you run OWASP Libmodsecurity3 or 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.

CVE-2026-30923: OWASP libModSecurity3 denial of service in t:hexDecode transformation

Q: Is there a fix for CVE-2026-30923?

A patch was published on 2026-04-28: Version 3.0.15 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-30923 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-30923?

Check whether you run OWASP Libmodsecurity3 or 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.

CVE-2026-30923 · Severity: high · CVSS 7.5 · Published 2026-05-05

ModSecurity is a widely used web application firewall (WAF) that protects web servers like Apache and Nginx from malicious traffic. A flaw in how the firewall processes certain data transformations allows an attacker to crash the firewall's worker processes by sending a specially crafted web request. This results in a denial of service, preventing legitimate users from accessing the protected website until the attack stops and the processes restart.

Technologies: OWASP Modsecurity. Vendors: OWASP.

Quick answers

Is CVE-2026-30923 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-30923 being exploited in the wild.
How severe is CVE-2026-30923?: High severity, with a CVSS score of 7.5, published 5 May 2026.
Which products and versions are affected?: OWASP Libmodsecurity3 < 3.0.15.
Is there a fix for CVE-2026-30923?: A patch was published on 2026-04-28: Version 3.0.15 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-30923 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-30923?: Check whether you run OWASP Libmodsecurity3 or 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.

Technical details

A vulnerability exists in libModSecurity3 (ModSecurity v3) due to an out-of-bounds read (CWE-125) in the hex_decode.cc component. When a rule is configured to use the t:hexDecode transformation, the engine fails to properly handle query string parameters containing only a single character. This leads to a segmentation fault in the modsecurity::utils::string::x2c function during processing. A remote, unauthenticated attacker can exploit this by sending repeated HTTP requests with a single-character parameter to crash WAF worker processes, resulting in a denial of service (DoS). This issue is resolved in version 3.0.15; ModSecurity v2 is not affected.

Affected products

OWASP libModSecurity3 < 3.0.15

Timeline

2026-04-28: patched: Version 3.0.15 released
2026-05-05: advisory: NVD and GitHub advisories published

References

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