How severe is CVE-2026-30923?

CVE-2026-30923 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-30923 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-30923?

CVE-2026-30923 affects Owasp Modsecurity. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-30923?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-30923 have an EU (EUVD) identifier?

Yes. CVE-2026-30923 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27422.

When was CVE-2026-30923 published?

CVE-2026-30923 was published on 2026-05-05 and last updated on 2026-06-17.

CVE-2026-30923

CVE-2026-30923 is a high-severity vulnerability in Owasp Modsecurity with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.2
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27422
Weakness: CWE-125
Affected product: Owasp Modsecurity
Published: 2026-05-05
Last modified: 2026-06-17

Description

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15.

Frequently asked questions

What is CVE-2026-30923?: ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15.
How severe is CVE-2026-30923?: CVE-2026-30923 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-30923 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-30923?: CVE-2026-30923 affects Owasp Modsecurity. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-30923?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-30923 have an EU (EUVD) identifier?: Yes. CVE-2026-30923 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27422.
When was CVE-2026-30923 published?: CVE-2026-30923 was published on 2026-05-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:owasp:modsecurity:*:*:*:*:*:*:*:*

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