CVE-2015-8036 in ARM mbed TLS
Summary
by MITRE
Heap-based buffer overflow in ARM mbed TLS (formerly PolarSSL) 1.3.x before 1.3.14 and 2.x before 2.1.2 allows remote SSL servers to cause a denial of service (client crash) and possibly execute arbitrary code via a long session ticket name to the session ticket extension, which is not properly handled when creating a ClientHello message to resume a session. NOTE: this identifier was SPLIT from CVE-2015-5291 per ADT3 due to different affected version ranges.
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Analysis
by VulDB Data Team • 06/05/2026
The vulnerability CVE-2015-8036 represents a critical heap-based buffer overflow in ARM mbed TLS cryptographic library that affects versions 1.3.x before 1.3.14 and 2.x before 2.1.2. This flaw resides in the handling of session ticket extensions during SSL/TLS client-side session resumption operations, specifically when processing long session ticket names within the ClientHello message construction. The vulnerability stems from inadequate bounds checking and memory allocation handling when the library processes session tickets provided by remote SSL servers, creating a potential attack surface that could be exploited by malicious actors controlling the SSL server.
The technical implementation of this vulnerability occurs within the session ticket extension processing logic where the mbed TLS library fails to properly validate the length of session ticket names before attempting to copy or process them into internal heap buffers. When a remote SSL server provides an excessively long session ticket name, the library's buffer management routines do not adequately check against predetermined maximum lengths, leading to memory corruption through heap overflow conditions. This type of vulnerability maps directly to CWE-121 Heap-based Buffer Overflow, which occurs when a program writes beyond the boundaries of heap-allocated memory blocks. The flaw manifests during the ClientHello message generation phase when the client attempts to resume a previous TLS session using a session ticket provided by the server, making it particularly dangerous in scenarios involving automated client-side connections or applications that automatically attempt session resumption.
The operational impact of CVE-2015-8036 extends beyond simple denial of service to potentially enable remote code execution, making it a severe security concern for affected systems. When exploited, the buffer overflow can cause client applications to crash due to memory corruption, leading to denial of service conditions that disrupt legitimate user access to services. However, the more concerning aspect is the potential for arbitrary code execution, which could allow attackers to gain control of vulnerable client systems when they process malicious session tickets from compromised servers. This vulnerability affects any application or system that relies on mbed TLS for SSL/TLS functionality, including web browsers, mobile applications, embedded devices, and network infrastructure components that utilize this cryptographic library for secure communications. The attack vector requires a remote SSL server to be compromised or under attacker control, making it particularly dangerous in scenarios where clients automatically attempt to resume sessions with servers they trust.
Mitigation strategies for CVE-2015-8036 should prioritize immediate patching of affected mbed TLS installations to versions 1.3.14 or 2.1.2 and later, which contain the necessary fixes for proper session ticket name length validation. Organizations should implement comprehensive vulnerability management processes to identify all systems utilizing affected mbed TLS versions and ensure timely updates are deployed across their infrastructure. Network administrators should consider implementing additional monitoring and intrusion detection measures to detect potential exploitation attempts, particularly focusing on unusual session ticket processing patterns or client crashes. The ATT&CK framework categorizes this vulnerability under T1210 Exploitation of Remote Services, as it involves exploitation of a service through malformed session tickets, and T1059 Command and Scripting Interpreter, since successful exploitation could enable attackers to execute arbitrary commands on vulnerable client systems. System hardening measures including restricting session ticket processing capabilities where possible and implementing proper input validation at all layers of the communication stack will further reduce the attack surface and potential impact of this vulnerability.