Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
CWE-832 Base Incomplete
Unlock of a Resource that is not Locked
This vulnerability occurs when a program tries to unlock a resource, such as a mutex or semaphore, that is not currently in a locked state.
Definition
What is CWE-832?
This vulnerability occurs when a program tries to unlock a resource, such as a mutex or semaphore, that is not currently in a locked state.
Attempting to unlock a resource that isn't locked is a logic error that can lead to unpredictable system behavior. The specific consequences depend heavily on the underlying locking mechanism, but often involve corrupting the resource's internal state or the memory structures used to manage lock ownership. This corruption can trigger crashes, cause data races, or leave the resource in an inconsistent state for subsequent operations.
For developers, this highlights the importance of maintaining strict symmetry between lock and unlock calls. Always ensure your unlock logic is only executed on a code path where a successful lock was previously acquired. Using RAII (Resource Acquisition Is Initialization) patterns or language constructs like `synchronized` blocks can help automate this pairing and prevent such manual management errors.
Real-world impact
Real-world CVEs caused by CWE-832
-
function in OS kernel unlocks a mutex that was not previously locked, causing a panic or overwrite of arbitrary memory.
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Chain: OS kernel does not properly handle a failure of a function call (CWE-755), leading to an unlock of a resource that was not locked (CWE-832), with resultant crash.
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OS kernel performs an unlock in some incorrect circumstances, leading to panic.
How attackers exploit it
Step-by-step attacker path
- 1
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 4
Iterate until the response leaks data, executes attacker code, or escalates privileges.
Vulnerable code example
Vulnerable pseudo
MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} Secure code example
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-832
- Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
- Implementation Validate input at trust boundaries; use allowlists, not denylists.
- Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
- Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
- Operation Monitor logs for the runtime signals listed in the next section.
Detection signals
How to detect CWE-832
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
CWE-832
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Frequently asked questions What is CWE-832?
How serious is CWE-832?
What languages or platforms are affected by CWE-832?
How can I prevent CWE-832?
How does Plexicus detect and fix CWE-832?
Where can I learn more about CWE-832?
Frequently asked questions
What is CWE-832?
This vulnerability occurs when a program tries to unlock a resource, such as a mutex or semaphore, that is not currently in a locked state.
How serious is CWE-832?
MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.
What languages or platforms are affected by CWE-832?
MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.
How can I prevent CWE-832?
Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.
How does Plexicus detect and fix CWE-832?
Plexicus's SAST engine matches the data-flow signature for CWE-832 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-832?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/832.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-832
CWE-667 Parent
Improper Locking
This vulnerability occurs when a program fails to correctly acquire or release a lock on a shared resource, such as a file, database…
CWE-1232 Sibling
Improper Lock Behavior After Power State Transition
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CWE-1233 Sibling
Security-Sensitive Hardware Controls with Missing Lock Bit Protection
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CWE-1234 Sibling
Hardware Internal or Debug Modes Allow Override of Locks
Hardware debug modes or internal states can bypass critical system lock protections, allowing unauthorized changes to device configuration.
CWE-412 Sibling
Unrestricted Externally Accessible Lock
This vulnerability occurs when a system correctly checks for a lock's existence, but an unauthorized external actor can control or…
CWE-413 Sibling
Improper Resource Locking
This vulnerability occurs when an application fails to properly lock a shared resource, such as a file or memory location, before…
CWE-414 Sibling
Missing Lock Check
This vulnerability occurs when software fails to verify that a proper synchronization lock is active before accessing or modifying a…
CWE-609 Sibling
Double-Checked Locking
Double-checked locking is an insufficient synchronization pattern where a program checks a resource's state, acquires a lock, and checks…
CWE-764 Sibling
Multiple Locks of a Critical Resource
This vulnerability occurs when a critical resource, such as a file, data structure, or connection, is locked more times than the software…
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