CWE-122: Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Consequences

• Availability: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory)
• Integrity, Confidentiality, Availability, Access Control: Execute Unauthorized Code or Commands, Bypass Protection Mechanism, Modify Memory
• Integrity, Confidentiality, Availability, Access Control, Other: Execute Unauthorized Code or Commands, Bypass Protection Mechanism, Other

How to prevent it

• Pre-design: Use a language or compiler that performs automatic bounds checking.
• Architecture and Design: Use an abstraction library to abstract away risky APIs. Not a complete solution.
• Operation, Build and Compilation: Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
• Operation, Build and Compilation: Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
• Implementation: Implement and perform bounds checking on input.
• Implementation: Do not use dangerous functions such as gets. Look for their safe equivalent, which checks for the boundary.
• Operation: Use OS-level preventative functionality. This is not a complete solution, but it provides some defense in depth.

Recent advisories

• GHSA-8g5g-8vmr-9782 — Pillow: Heap buffer overflow in ImagingJpegDecode
• GHSA-5x8w-8jj5-q52h — Pillow: Heap buffer overflow in FlashPix (FPX) JPEG decoding leads to code execution
• GHSA-462x-pgg6-55fp — Pillow tiled-TIFF decoder reads past tile buffer in copy4 (Unpack.c:1290)
• GHSA-332p-7hrc-92wf — Pillow: Heap buffer overflow in _tiffWriteProc when saving TIFF to BytesIO
• CVE-2026-94127 — When a BIG-IP APM access policy and an OAuth profile are configured on a virtual server, specific malicious traffic can lead to remote code execution (RCE).
• GHSA-rgj7-g3m4-5g8c — sharp: Vulnerabilities in libheif: GHSA-g89c-p67h-r497 and GHSA-2jg2-4ch7-h545
• CVE-2026-85880 — Heap-based buffer overflow in Windows ALPC allows an authorized attacker to elevate privileges locally.
• GHSA-jqhp-238x-qhgf — Microsoft Security Advisory CVE-2026-62886 – .NET Elevation of Privilege Vulnerability
• GHSA-vg44-h755-9hw7 — Microsoft Security Advisory CVE-2026-62871 – .NET Elevation of Privilege Vulnerability
• GHSA-76q6-2p6h-xjqr — ImageMagick: Heap Buffer Over-Write in X11 import with crafted window title
• CVE-2026-53362 — ipv6: account for fraggap on the paged allocation path
• GHSA-5rff-8f7c-8jmw — Open Babel has out-of-bounds write in ORCA nAtoms parser (second variant)
• GHSA-rj4c-r689-cm87 — Open Babel has out-of-bounds write in ORCA nAtoms parser
• GHSA-x2f5-4prf-w687 — Ruby json: JSON generator heap buffer overflow when streaming to an IO
• GHSA-35w3-pjm6-wj95 — Oj: Heap Buffer Overflow in Oj.dump Exception Serialization via Large Indent

All advisories for CWE-122