How severe is CVE-2019-11391?

CVE-2019-11391 has a CVSS 3.x base score of 5.3, rated medium 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 low.

Is CVE-2019-11391 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-11391?

CVE-2019-11391 affects Modsecurity Owasp Modsecurity Core Rule Set. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2019-11391?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2019-11391 published?

CVE-2019-11391 was published on 2019-04-21 and last updated on 2026-06-17.

CVE-2019-11391

CVE-2019-11391 is a medium-severity vulnerability in Modsecurity Owasp Modsecurity Core Rule Set with a CVSS 3.x base score of 5.3. 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-400.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Modsecurity Owasp Modsecurity Core Rule Set
Published: 2019-04-21
Last modified: 2026-06-17

Description

An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-933-APPLICATION-ATTACK-PHP.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with $a# at the beginning and nested repetition operators. NOTE: the software maintainer disputes that this is a vulnerability because the issue cannot be exploited via ModSecurity

Frequently asked questions

What is CVE-2019-11391?: An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-933-APPLICATION-ATTACK-PHP.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with $a# at the beginning and nested repetition operators. NOTE: the software maintainer disputes that this is a vulnerability because the issue cannot be exploited via ModSecurity
How severe is CVE-2019-11391?: CVE-2019-11391 has a CVSS 3.x base score of 5.3, rated medium 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 low.
Is CVE-2019-11391 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-11391?: CVE-2019-11391 affects Modsecurity Owasp Modsecurity Core Rule Set. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-11391?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-11391 published?: CVE-2019-11391 was published on 2019-04-21 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:modsecurity:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*

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