Description

A flaw was found in libstdc++. An integer overflow can occur when processing large inputs to the C++ `new` operator. This vulnerability could lead to an undersized memory allocation, potentially causing memory corruption or application instability.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.7",
  "pubDate": "2026-09-22T13:17:13.300Z",
  "pubdate": "2026-09-22T13:17:13.300Z",
  "executiveSummary": "This vulnerability is an integer overflow flaw identified within the libstdc++ library, specifically impacting the internal processing logic of the C++ 'new' operator.\nThe vulnerability manifests when the library processes excessively large input sizes for memory allocation, leading to an integer wrap-around condition.\nThe primary security impact is the allocation of an undersized heap buffer, which fails to accommodate the intended data volume. This discrepancy creates a significant risk of heap-based memory corruption, potentially leading to arbitrary code execution, unauthorized data access, or forced application instability/crashes.\nAffected systems include any environment utilizing libstdc++ that performs dynamic memory allocation via the 'new' operator without sufficient size validation of user-supplied input.\nThe risk implication is high, as memory corruption vulnerabilities often allow attackers to bypass standard software protections.\nExploitation requires the attacker to influence the size parameter passed to the memory allocation routine, typically through untrusted input sources. No specific authentication is required, as the flaw resides in fundamental memory management routines that are often reachable via standard application interfaces.",
  "technicalDetails": "The root cause of this vulnerability lies in an improper calculation of memory allocation size within libstdc++. When the C++ 'new' operator is invoked, the library calculates the number of bytes required for the requested object. If the input parameters are maliciously crafted to exceed the maximum value representable by the size_t type, the calculation suffers from an integer overflow.\nIn standard implementations, the resulting truncated value is passed directly to the underlying allocation routine (such as malloc). Because the allocated buffer is significantly smaller than the actual data intended to be stored, subsequent write operations result in a heap-based buffer overflow.\nThe exploitation flow begins when an application accepts external or unvalidated input that influences the allocation size during object instantiation. An attacker provides a size value that, when processed by the library's arithmetic, causes an overflow. The heap allocator subsequently returns a pointer to a block of memory that is too small for the intended payload. When the application proceeds to copy data into this buffer, it performs an out-of-bounds write.\nThis out-of-bounds write allows an attacker to overwrite adjacent heap metadata, object pointers, or virtual function tables (vtable). By corrupting vtable pointers or sensitive application data structures, an attacker may achieve control over the application's execution flow, redirected to attacker-controlled memory or existing gadget chains (ROP/JOP).\nBecause libstdc++ is a foundational component of the C++ runtime environment, this vulnerability is not restricted to a specific network protocol or service. It is inherent to any process that dynamically allocates memory based on externally influenced values. There are no authentication or privilege requirements to trigger the memory corruption, provided the vulnerable code path is reachable through the application's exposed interface.\nPost-exploitation impact ranges from local Denial of Service (DoS) due to memory corruption-induced crashes to full process compromise, depending on the memory layout and the presence of exploit mitigation techniques like Address Space Layout Randomization (ASLR) or Data Execution Prevention (DEP). The effectiveness of such mitigations may be reduced if an attacker can combine this integer overflow with an information disclosure vulnerability to determine memory addresses."
}