Information disclosure in Linux kernel - CVE-2021-3773

Vulnerability identifier: #VU63920

CSH Severity: Medium

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

CVE-ID: CVE-2021-3773

CWE-ID: CWE-200

Exploitation vector: Remote access

Exploit availability: Public exploit is available

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to excessive data output in the netfilter. A remote attacker can infer openvpn connection endpoint informationand gain unauthorized access to sensitive information on the system.

Linux kernel
Red Hat Enterprise Linux for Real Time
Red Hat Enterprise Linux for Real Time for NFV
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat CodeReady Linux Builder for x86_64
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for ARM 64
Anolis OS
Fedora
Migration Toolkit for Containers
Red Hat Advanced Cluster Management for Kubernetes
kernel-doc
kernel-abi-stablelists
python3-perf
perf
kernel-tools-libs
kernel-tools
kernel-modules-extra
kernel-modules
kernel-headers
kernel-devel
kernel-debug-modules-extra
kernel-debug-modules
kernel-debug-devel
kernel-debug-core
kernel-debug
kernel-cross-headers
kernel-core
kernel
bpftool
kernel (Red Hat package)
kernel-rt (Red Hat package)

Install updates from vendor's website.

Linux kernel - update to 5.14.0-49.el9
Migration Toolkit for Containers - addressed in versions 1.6.5, 1.7.2
Red Hat Advanced Cluster Management for Kubernetes - addressed in versions 2.3.11, 2.4.5, 2.5.0
kernel-doc - update to 4.18.0-372.9.1
kernel-abi-stablelists - update to 4.18.0-372.9.1
python3-perf - update to 4.18.0-372.9.1
perf - update to 4.18.0-372.9.1
kernel-tools-libs - update to 4.18.0-372.9.1
kernel-tools - update to 4.18.0-372.9.1
kernel-modules-extra - update to 4.18.0-372.9.1
kernel-modules - update to 4.18.0-372.9.1
kernel-headers - update to 4.18.0-372.9.1
kernel-devel - update to 4.18.0-372.9.1
kernel-debug-modules-extra - update to 4.18.0-372.9.1
kernel-debug-modules - update to 4.18.0-372.9.1
kernel-debug-devel - update to 4.18.0-372.9.1
kernel-debug-core - update to 4.18.0-372.9.1
kernel-debug - update to 4.18.0-372.9.1
kernel-cross-headers - update to 4.18.0-372.9.1
kernel-core - update to 4.18.0-372.9.1
kernel - update to 4.18.0-372.9.1
bpftool - update to 4.18.0-372.9.1
kernel (Red Hat package) - update to 4.18.0-372.9.1.el8
kernel-rt (Red Hat package) - update to 4.18.0-372.9.1.rt7.166.el8
kernel - addressed in versions 5.15.15-100.fc34, 5.15.15-200.fc35

• Exploit #10224 - CVE-2021-3773 (This script exploits the "Port Shadow" vulnerability (CVE-2021-3773) in OpenVPN servers using Netfilter for NAT.) (July 19, 2024)

• https://bugzilla.redhat.com/show_bug.cgi?id=2004949

• Multiple vulnerabilities in Red Hat Advanced Cluster Management 2.4
• Multiple vulnerabilities in Red Hat Advanced Cluster Management 2.3
• Multiple vulnerabilities in Red Hat Migration Toolkit for Containers (MTC)
• Red Hat Enterprise Linux 8 update for kernel-rt
• Red Hat Enterprise Linux 8 update for kernel
• Multiple vulnerabilities in Migration Toolkit for Containers 1.6
• Multiple vulnerabilities in Red Hat Advanced Cluster Management for Kubernetes 2
• Fedora 34 update for kernel
• Fedora 35 update for kernel
• Anolis OS update for kernel