Home/CWE/Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Weakness

Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CWE-120 · Base · Incomplete

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

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Weakness Relationships

Where this weakness sits in the CWE hierarchy. Walk up to broader classes or down to more specific variants.
Parent of this (broader)
ChildOfCWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer
ChildOfCWE-20 · Improper Input Validation
ChildOfCWE-787 · Out-of-bounds Write
Children (more specific)
ParentOfCWE-785 · Use of Path Manipulation Function without Maximum-sized Buffer
Related
CanPrecedeCWE-123 · Write-what-where Condition
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Attack Patterns (CAPEC)

13
How adversaries exploit this weakness, per MITRE CAPEC.
CAPEC-10Buffer Overflow via Environment Variables
CAPEC-100Overflow Buffers
CAPEC-14Client-side Injection-induced Buffer Overflow
CAPEC-24Filter Failure through Buffer Overflow
CAPEC-42MIME Conversion
CAPEC-44Overflow Binary Resource File
CAPEC-45Buffer Overflow via Symbolic Links
CAPEC-46Overflow Variables and Tags
CAPEC-47Buffer Overflow via Parameter Expansion
CAPEC-67String Format Overflow in syslog()
CAPEC-8Buffer Overflow in an API Call
CAPEC-9Buffer Overflow in Local Command-Line Utilities
CAPEC-92Forced Integer Overflow
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CVEs With This Weakness

5,085
A sample of the 5,085 CVEs tagged with this weakness.
CVECVE-2026-8776
CVECVE-2026-8775
CVECVE-2026-8764
CVECVE-2026-8260
CVECVE-2026-8137
CVECVE-2026-7857
CVECVE-2026-7856
CVECVE-2026-7855
CVECVE-2026-7854
CVECVE-2026-7853
CVECVE-2026-7750
CVECVE-2026-7749
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Nuclei Scanner Templates

2
Open-source Nuclei templates that detect this weakness class - an actionable scan-for-it pivot. Licensed under the ProjectDiscovery / Nuclei terms.
criticalApache HTTP Server - Remote Code Execution
mediumFileZilla Server < 0.9.31 - SSL/TLS Packet Overflow DoS
External lookups - second-class, for what we don’t hold ourselves
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