CVE-2024-12243 in GnuTLS
Summary
by MITRE • 02/10/2025
A flaw was found in GnuTLS, which relies on libtasn1 for ASN.1 data processing. Due to an inefficient algorithm in libtasn1, decoding certain DER-encoded certificate data can take excessive time, leading to increased resource consumption. This flaw allows a remote attacker to send a specially crafted certificate, causing GnuTLS to become unresponsive or slow, resulting in a denial-of-service condition.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/06/2025
The vulnerability identified as CVE-2024-12243 represents a significant denial-of-service weakness within the GnuTLS cryptographic library ecosystem. This flaw specifically targets the libtasn1 component responsible for processing ASN.1 encoded data structures commonly found in digital certificates. The issue manifests when GnuTLS encounters certain DER-encoded certificate data that triggers inefficient algorithmic behavior within libtasn1's decoding routines. This inefficient processing causes substantial delays in certificate validation operations, effectively consuming excessive computational resources and leading to system unresponsiveness. The vulnerability operates at the intersection of cryptographic protocol handling and resource management, creating a scenario where legitimate security operations become weapons of disruption.
The technical implementation of this vulnerability stems from algorithmic inefficiencies within libtasn1's ASN.1 parsing mechanisms. When processing specific certificate structures, particularly those containing nested or deeply recursive ASN.1 elements, the library's decoding algorithm exhibits exponential time complexity behavior rather than the expected linear or polynomial performance characteristics. This algorithmic flaw allows an attacker to construct malicious certificate data that, when processed by GnuTLS, causes the system to enter prolonged processing states. The vulnerability demonstrates characteristics consistent with CWE-20, "Improper Input Validation," and CWE-400, "Uncontrolled Resource Consumption," as it exploits the library's handling of structured data to consume excessive computational resources. The impact extends beyond simple performance degradation to complete system unresponsiveness, particularly in high-throughput environments where certificate validation occurs frequently.
From an operational perspective, this vulnerability poses a serious threat to systems relying on GnuTLS for secure communications, including web servers, email servers, and any application handling TLS/SSL certificate validation. The remote exploitation nature means attackers can trigger the denial-of-service condition without requiring local access or authentication, making it particularly dangerous in production environments. The resource consumption pattern typically results in increased CPU utilization, memory pressure, and potential process starvation, which can cascade into broader system instability. This vulnerability affects the fundamental security infrastructure of systems, as it targets the certificate validation process that ensures the authenticity and integrity of secure communications. Organizations using GnuTLS for TLS implementations face potential service disruption that could last from minutes to hours depending on system resources and the complexity of the malicious certificate data.
Mitigation strategies for CVE-2024-12243 focus on both immediate remediation and long-term architectural improvements. The primary recommendation involves updating to patched versions of both GnuTLS and libtasn1 components, which contain algorithmic optimizations that prevent the excessive processing time. Network administrators should implement certificate validation timeouts and rate limiting mechanisms to prevent prolonged processing of suspicious certificate data. Additionally, deploying certificate pre-validation systems that can identify and reject potentially malicious certificate structures before they reach the core GnuTLS processing engine provides an effective defense layer. Organizations should also consider implementing intrusion detection systems that can identify unusual certificate processing patterns and alert security teams to potential exploitation attempts. The vulnerability highlights the importance of proper algorithmic complexity analysis in cryptographic libraries and aligns with ATT&CK technique T1499.004, "Resource Hijacking," as it exploits system resources to disrupt normal operations. Implementation of these mitigations requires careful testing to ensure they do not inadvertently affect legitimate certificate processing while providing adequate protection against the specific denial-of-service vector.