CVE-2025-48965 in TLS
Summary
by MITRE • 07/20/2025
Mbed TLS before 3.6.4 has a NULL pointer dereference because mbedtls_asn1_store_named_data can trigger conflicting data with val.p of NULL but val.len greater than zero.
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Analysis
by VulDB Data Team • 08/07/2025
The vulnerability identified as CVE-2025-48965 represents a critical NULL pointer dereference flaw within the Mbed TLS cryptographic library version 3.6.4 and earlier. This issue stems from improper validation of ASN.1 data structures during certificate processing, specifically when handling named data elements. The flaw manifests when the mbedtls_asn1_store_named_data function encounters a scenario where the pointer val.p is NULL while val.len maintains a value greater than zero, creating a dangerous condition that can lead to application crashes or potential security exploitation.
The technical root cause of this vulnerability lies in the ASN.1 parsing logic within Mbed TLS where the library fails to properly validate the consistency of data pointers and length fields. When processing certificate data structures, the function attempts to store named data elements without adequate checks to ensure that a non-zero length field corresponds to a valid memory pointer. This inconsistency creates a scenario where subsequent operations attempting to dereference the NULL pointer result in immediate system termination. The vulnerability specifically affects the certificate processing pipeline and can be triggered during any operation involving ASN.1 decoding of certificate attributes, making it particularly dangerous in environments where certificate validation is critical for security operations.
The operational impact of CVE-2025-48965 extends beyond simple application crashes, potentially enabling denial of service attacks against systems relying on Mbed TLS for secure communications. Attackers could craft malicious certificates or certificate chains that trigger this NULL pointer dereference during normal processing, causing service interruptions and potentially allowing for more sophisticated exploitation techniques. The vulnerability affects any system or application using Mbed TLS versions prior to 3.6.4, including embedded devices, web servers, VPN implementations, and IoT systems that depend on secure communication protocols. This makes the impact particularly severe in environments where continuous availability is critical, as the vulnerability can be exploited to cause persistent service disruptions without requiring elevated privileges or complex attack vectors.
Mitigation strategies for CVE-2025-48965 primarily focus on upgrading to Mbed TLS version 3.6.4 or later, where the NULL pointer dereference has been addressed through enhanced input validation and proper handling of edge cases in ASN.1 parsing. Organizations should conduct comprehensive vulnerability assessments to identify all systems and applications utilizing affected Mbed TLS versions, particularly those handling certificate validation or secure communications. Additionally, implementing proper input sanitization and validation measures at application layers can provide additional defense-in-depth against potential exploitation attempts. The vulnerability aligns with CWE-476, which specifically addresses NULL pointer dereference conditions, and represents a typical example of how improper validation of cryptographic data structures can lead to system instability and potential security breaches. Security teams should also consider monitoring for exploitation attempts through network traffic analysis and system logs, as the vulnerability may be detected through abnormal process termination patterns or service disruption events.