NULL pointer dereference in Apache HTTP Server - CVE-2021-41524

Vulnerability identifier: #VU57062

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-2021-41524

CWE-ID: CWE-476

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 a NULL pointer dereference error when processing HTTP/2 requests. A remote attacker can send a specially crafted HTTP/2 request to the affected Apache HTTP server and perform a denial of service (DoS) attack.

Apache HTTP Server
Amazon Linux AMI
Gentoo Linux
Slackware Linux
Fedora
jbcs-httpd24-openssl-pkcs11 (Red Hat package)
jbcs-httpd24-openssl-chil (Red Hat package)
jbcs-httpd24-brotli (Red Hat package)
jbcs-httpd24-apr-util (Red Hat package)
jbcs-httpd24-apr (Red Hat package)
jbcs-httpd24-mod_http2 (Red Hat package)
jbcs-httpd24-nghttp2 (Red Hat package)
jbcs-httpd24-mod_md (Red Hat package)
jbcs-httpd24-httpd (Red Hat package)
jbcs-httpd24-mod_security (Red Hat package)
jbcs-httpd24-jansson (Red Hat package)
jbcs-httpd24-curl (Red Hat package)
jbcs-httpd24-mod_proxy_cluster (Red Hat package)
httpd
www-servers/apache
app-admin/apache-tools
JBoss Core Services

Install update from vendor's website.

Apache HTTP Server - update to 2.4.50
jbcs-httpd24-openssl-pkcs11 (Red Hat package) - addressed in versions 0.4.10-31.el7jbcs, 0.4.10-31.el8jbcs
jbcs-httpd24-openssl-chil (Red Hat package) - addressed in versions 1.0.0-16.el7jbcs, 1.0.0-16.el8jbcs
jbcs-httpd24-brotli (Red Hat package) - addressed in versions 1.0.9-2.el7jbcs, 1.0.9-2.el8jbcs
jbcs-httpd24-apr-util (Red Hat package) - addressed in versions 1.6.1-98.el7jbcs, 1.6.1-98.el8jbcs
jbcs-httpd24-apr (Red Hat package) - addressed in versions 1.7.0-6.el7jbcs, 1.7.0-6.el8jbcs
jbcs-httpd24-mod_http2 (Red Hat package) - addressed in versions 1.15.19-17.el7jbcs, 1.15.19-17.el8jbcs
jbcs-httpd24-nghttp2 (Red Hat package) - addressed in versions 1.43.0-10.el7jbcs, 1.43.0-10.el8jbcs
jbcs-httpd24-mod_md (Red Hat package) - addressed in versions 2.4.0-15.el7jbcs, 2.4.0-15.el8jbcs
jbcs-httpd24-httpd (Red Hat package) - addressed in versions 2.4.51-28.el7jbcs, 2.4.51-28.el8jbcs
jbcs-httpd24-mod_security (Red Hat package) - addressed in versions 2.9.3-19.el7jbcs, 2.9.3-19.el8jbcs
jbcs-httpd24-jansson (Red Hat package) - addressed in versions 2.14-1.el7jbcs, 2.14-1.el8jbcs
jbcs-httpd24-curl (Red Hat package) - addressed in versions 7.83.1-6.el7jbcs, 7.83.1-6.el8jbcs
jbcs-httpd24-mod_proxy_cluster (Red Hat package) - addressed in versions 1.3.17-9.el7jbcs, 1.3.17-9.el8jbcs
httpd - addressed in versions 2.4.50-1.fc33, 2.4.50-1.fc34, 2.4.50-1.fc35
JBoss Core Services - update to 2.4.51
www-servers/apache - update to 2.4.54
app-admin/apache-tools - update to 2.4.54

• https://httpd.apache.org/security/vulnerabilities_24.html

• Multiple vulnerabilities in Apache HTTP Server
• Slackware Linux update for httpd
• Amazon Linux AMI update for httpd24
• Gentoo update for Apache HTTPD
• Multiple vulnerabilities in Red Hat JBoss Core Services
• Fedora 33 update for httpd
• Fedora 35 update for httpd
• Fedora 34 update for httpd