CWE-667

Class Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Draft MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE
Improper Locking

Description

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Top Monitored CVEs

CVE-2020-24606
HIGH
7.5 5.2%
2020-08-24
CVE-2025-43510
HIGH KEV
7.8 0.3%
2025-12-12

Consequences

Availability — DoS: Resource Consumption (CPU)

Inconsistent locking discipline can lead to deadlock.

Mitigations

Phase: Implementation

Use industry standard APIs to implement locking mechanism.

Detection

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)