CVE-2016-6131 in libiberty
Summary
by MITRE
The demangler in GNU Libiberty allows remote attackers to cause a denial of service (infinite loop, stack overflow, and crash) via a cycle in the references of remembered mangled types.
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Analysis
by VulDB Data Team • 08/11/2020
The vulnerability identified as CVE-2016-6131 resides within the GNU Libiberty library, specifically affecting its demangler component that is responsible for converting mangled C++ symbol names back into their human-readable form. This flaw represents a critical security issue that can be exploited by remote attackers to disrupt system operations through carefully crafted input sequences. The demangler is commonly used in debugging tools, profilers, and other development utilities that need to process symbol information from compiled binaries, making it a widely deployed component across various software ecosystems.
The technical root cause of this vulnerability stems from inadequate handling of cyclic references within the mangled type information structure. When the demangler encounters a cycle in the references of remembered mangled types, it enters an infinite loop during the demangling process, consuming excessive computational resources and eventually leading to a stack overflow condition. This behavior occurs because the demangler lacks proper cycle detection mechanisms in its parsing algorithm, causing it to repeatedly traverse the same reference paths without termination. The flaw manifests when processing specially crafted mangled symbol names that contain self-referential or circular type references, which can be embedded within compiled binary files or debug information.
The operational impact of CVE-2016-6131 extends beyond simple denial of service conditions to potentially compromise system availability and stability. Remote attackers can exploit this vulnerability by providing maliciously constructed mangled symbol data to applications that utilize the affected GNU Libiberty demangler, resulting in system crashes, resource exhaustion, and service unavailability. This vulnerability affects a broad range of software that depends on Libiberty, including but not limited to GCC compiler toolchain components, debuggers like gdb, profiling tools, and various binary analysis utilities. The infinite loop and stack overflow conditions can cause applications to become unresponsive or terminate unexpectedly, potentially leading to cascading failures in systems that rely on these tools for development and debugging operations.
Mitigation strategies for CVE-2016-6131 primarily involve updating to patched versions of GNU Libiberty where the demangler has been enhanced with proper cycle detection and handling mechanisms. System administrators should prioritize applying security updates to all affected software components that utilize the vulnerable library, particularly in environments where untrusted input processing occurs. Additionally, implementing input validation measures and sandboxing techniques can help reduce the attack surface by preventing malicious mangled symbol data from reaching the vulnerable demangler functionality. Organizations should also consider monitoring for unusual resource consumption patterns that might indicate exploitation attempts, as the vulnerability typically manifests through excessive CPU usage or memory allocation during demangling operations. This vulnerability aligns with CWE-838, which addresses improper handling of data structures, and relates to ATT&CK technique T1499.004 for resource exhaustion attacks, demonstrating the importance of robust input validation and defensive programming practices in security-critical software components.