CVE-2022-2663 in Linux
Summary
by MITRE • 09/02/2022
An issue was found in the Linux kernel in nf_conntrack_irc where the message handling can be confused and incorrectly matches the message. A firewall may be able to be bypassed when users are using unencrypted IRC with nf_conntrack_irc configured.
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Analysis
by VulDB Data Team • 05/26/2026
The vulnerability identified as CVE-2022-2663 resides within the Linux kernel's netfilter subsystem, specifically in the nf_conntrack_irc module responsible for tracking internet relay chat connections. This flaw represents a significant security weakness that can potentially undermine network firewalls and access control mechanisms. The issue manifests when the connection tracking module fails to properly parse and interpret IRC protocol messages, leading to incorrect state determination for network connections. The vulnerability falls under the category of protocol handling errors that can result in improper packet filtering decisions.
The technical root cause of this vulnerability stems from inadequate message parsing logic within the nf_conntrack_irc module. When processing IRC traffic without encryption, the kernel's connection tracking component incorrectly interprets certain message patterns, causing it to misclassify connection states. This misclassification occurs because the module fails to properly distinguish between different types of IRC messages or handle edge cases in message formatting. The flaw allows an attacker to craft specific IRC messages that can confuse the connection tracking logic, potentially causing the firewall to treat malicious traffic as legitimate or vice versa. This behavior directly violates the fundamental principles of network security and connection state management that are essential for proper firewall operation.
The operational impact of CVE-2022-2663 extends beyond simple packet filtering failures, as it can enable persistent firewall bypasses for users who rely on unencrypted IRC communications. When deployed in production environments, this vulnerability can allow unauthorized network access or data exfiltration by exploiting the misconfigured connection tracking behavior. Network administrators who have configured nf_conntrack_irc for IRC traffic monitoring or access control may find their security policies effectively neutralized, as the module's flawed message handling can be leveraged to circumvent intended restrictions. The vulnerability is particularly concerning in environments where unencrypted IRC traffic flows through firewalled systems, as the attack surface expands significantly when proper connection tracking fails.
Security mitigation strategies for this vulnerability should focus on immediate kernel updates and patches provided by the Linux kernel development team. Organizations should prioritize applying the latest security patches that address the specific message parsing flaws in the nf_conntrack_irc module. Additionally, network administrators should consider disabling the nf_conntrack_irc module if unencrypted IRC traffic is not strictly required, as this eliminates the attack surface entirely. The vulnerability aligns with CWE-129, which addresses improper input validation in protocol handlers, and can be mapped to ATT&CK technique T1071.004 for application layer protocol manipulation. Implementing additional network monitoring and anomaly detection can help identify exploitation attempts, while enforcing encrypted IRC communications through TLS can provide defense in depth against this specific vulnerability.