CVE-2023-3341 in BIND
Summary
by MITRE • 09/20/2023
The code that processes control channel messages sent to `named` calls certain functions recursively during packet parsing. Recursion depth is only limited by the maximum accepted packet size; depending on the environment, this may cause the packet-parsing code to run out of available stack memory, causing `named` to terminate unexpectedly. Since each incoming control channel message is fully parsed before its contents are authenticated, exploiting this flaw does not require the attacker to hold a valid RNDC key; only network access to the control channel's configured TCP port is necessary. This issue affects BIND 9 versions 9.2.0 through 9.16.43, 9.18.0 through 9.18.18, 9.19.0 through 9.19.16, 9.9.3-S1 through 9.16.43-S1, and 9.18.0-S1 through 9.18.18-S1.
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Analysis
by VulDB Data Team • 12/02/2025
The vulnerability described in CVE-2023-3341 represents a critical stack-based buffer overflow condition within the BIND 9 DNS server implementation that stems from improper recursion handling during control channel message processing. This flaw exists in the recursive parsing functions that handle incoming control channel messages destined for the named daemon, creating a scenario where the stack memory consumption grows exponentially with each nested function call. The recursive code path lacks adequate depth limitations, allowing maliciously crafted packets to consume all available stack space and ultimately cause the named process to crash and terminate unexpectedly. The vulnerability's severity is amplified by its accessibility since authentication is deferred until after full packet parsing, meaning attackers can exploit this without possessing valid RNDC credentials. The affected versions span multiple release lines including 9.2.0 through 9.16.43, 9.18.0 through 9.18.18, 9.19.0 through 9.19.16, and their corresponding snapshot releases, indicating this is a widespread issue affecting the core DNS server functionality across multiple stable branches.
The technical implementation of this vulnerability demonstrates a classic stack exhaustion attack vector where the recursive parsing functions process control channel messages without adequate safeguards against deep recursion. When an attacker sends specially crafted packets to the configured TCP port for the control channel, the parsing code enters a recursive loop that consumes stack memory at an accelerating rate. The maximum recursion depth is directly tied to the packet size limits, making the vulnerability exploitable through carefully constructed payloads that maximize the recursive call depth. This type of vulnerability maps directly to CWE-674, which describes "Uncontrolled Recursion" and falls under the broader category of stack-based buffer overflows. The attack pattern aligns with ATT&CK technique T1210, "Exploitation of Remote Services," as it leverages network access to a configured service port to achieve denial of service. The lack of authentication requirements for exploitation makes this particularly dangerous in environments where control channel ports are exposed to untrusted networks or where default configurations are not properly secured.
The operational impact of CVE-2023-3341 extends beyond simple service disruption to potentially compromise entire DNS infrastructure availability. When the named daemon crashes due to stack exhaustion, it results in immediate denial of service for all DNS resolution requests handled by that server, affecting all dependent services and applications relying on DNS resolution. The vulnerability's ability to cause unexpected termination without requiring authentication credentials means that even networks with properly secured RNDC keys remain vulnerable if the control channel TCP port is accessible to attackers. This creates a significant risk for organizations that may have properly configured authentication but failed to properly firewall the control channel ports, leaving them exposed to this type of attack. The cascading effects can be particularly severe in hierarchical DNS deployments where multiple servers depend on each other for zone transfers, dynamic updates, and other control channel operations. Network administrators face the challenge of identifying vulnerable systems without having to rely on authentication mechanisms that are bypassed by this exploit, making detection and remediation more complex than typical authentication bypass scenarios.
Mitigation strategies for CVE-2023-3341 require immediate action to either upgrade affected BIND versions to patched releases or implement network-level protections. The most effective solution involves applying the security patches released by ISC that address the recursive parsing logic and introduce proper depth limitations to prevent stack exhaustion. Organizations should prioritize upgrading to BIND versions 9.16.44, 9.18.19, 9.19.17, or later, which contain the necessary fixes for this vulnerability. Network-level mitigations include firewalling control channel ports to restrict access to only trusted administrative hosts, implementing rate limiting on incoming connections, and monitoring for unusual packet patterns that might indicate exploitation attempts. Additionally, system administrators should consider implementing process monitoring and automatic restart mechanisms to minimize service disruption when attacks do occur. The vulnerability's nature makes it particularly important to review all network configurations and ensure that control channel ports are not exposed to untrusted networks, as the attack requires only network connectivity to the configured TCP port rather than any authentication credentials. Security teams should also implement logging and alerting for control channel activity to detect potential exploitation attempts and establish incident response procedures for handling such denial of service events.