Uncontrolled Recursion in ModSecurity - CVE-2021-42717

Vulnerability identifier: #VU59052

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2021-42717

CWE-ID: CWE-674

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to uncontrolled recursion when processing excessively nested JSON objects. A remote attacker can send a specially crafted HTTP request and consume all available worker processes and CPU resources.

ModSecurity
modsecurity-apache (Debian package)
libapache2-mod-security2 (Ubuntu package)
libapache2-modsecurity (Ubuntu package)
mod_security
mod_security-debugsource
mod_security-debuginfo
libmodsecurity
Fedora
Ubuntu
openEuler
Oracle HTTP Server
HPE OneView

Install updates from vendor's website.

ModSecurity - addressed in versions 2.9.5, 3.0.6
modsecurity-apache (Debian package) - addressed in versions 2.9.3-1+deb10u1, 2.9.3-3, 2.9.3-3+deb11u1
libapache2-mod-security2 (Ubuntu package) - addressed in versions Ubuntu Pro, 2.9.3-1ubuntu0.1
libapache2-modsecurity (Ubuntu package) - update to Ubuntu Pro
mod_security - update to 2.9.5-1
mod_security-debugsource - update to 2.9.5-1
mod_security-debuginfo - update to 2.9.5-1
libmodsecurity - update to 3.0.9-2.el7
HPE OneView - update to 8.90.00

• https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/

• Denial of service in ModSecurity
• Debian update for modsecurity-apache
• Multiple vulnerabilities in Oracle HTTP Server
• Fedora EPEL 7 update for libmodsecurity
• Ubuntu update for modsecurity-apache
• openEuler update for mod_security
• openEuler 20.03 LTS SP3 update for mod_security
• Multiple vulnerabilities in HPE OneView