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.)
CWE-824 Base Incomplete
Access of Uninitialized Pointer
This vulnerability occurs when a program tries to use a pointer variable before it has been assigned a valid memory address.
Definition
What is CWE-824?
This vulnerability occurs when a program tries to use a pointer variable before it has been assigned a valid memory address.
Using an uninitialized pointer means your code is reading from or writing to a random, unpredictable location in memory. This often crashes the program (causing a denial of service), but it can also lead to strange behavior, data corruption, or the execution of unintended functions if the pointer is called.
An attacker who can control or predict what value ends up in that uninitialized pointer gains significant power. By carefully manipulating memory layout, they might steer the pointer to a location of their choosing, potentially enabling code execution, privilege escalation, or other serious security breaches.
Real-world impact
Real-world CVEs caused by CWE-824
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LLM product has a free of an uninitialized pointer
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Chain: secure communications library does not initialize a local variable for a data structure (CWE-456), leading to access of an uninitialized pointer (CWE-824).
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Chain: C union member is not initialized (CWE-456), leading to access of invalid pointer (CWE-824)
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chain: unchecked return value (CWE-252) leads to free of invalid, uninitialized pointer (CWE-824).
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Pointer in structure is not initialized, leading to NULL pointer dereference (CWE-476) and system crash.
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Free of an uninitialized pointer.
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Improper handling of invalid signatures leads to free of invalid pointer.
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Invalid encoding triggers free of uninitialized pointer.
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-824
- 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-824
Plexicus auto-detects CWE-824 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-824?
How serious is CWE-824?
What languages or platforms are affected by CWE-824?
How can I prevent CWE-824?
How does Plexicus detect and fix CWE-824?
Where can I learn more about CWE-824?
Frequently asked questions
What is CWE-824?
This vulnerability occurs when a program tries to use a pointer variable before it has been assigned a valid memory address.
How serious is CWE-824?
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-824?
MITRE lists the following affected platforms: C, C++.
How can I prevent CWE-824?
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-824?
Plexicus's SAST engine matches the data-flow signature for CWE-824 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-824?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/824.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-824
CWE-119 Parent
Improper Restriction of Operations within the Bounds of a Memory Buffer
This vulnerability occurs when software accesses a memory buffer but reads from or writes to a location outside its allocated boundary.…
CWE-120 Sibling
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
This vulnerability occurs when a program copies data from one memory location to another without first verifying that the source data will…
CWE-123 Sibling
Write-what-where Condition
A write-what-where condition occurs when an attacker can control both the data written and the exact memory location where it's written,…
CWE-125 Sibling
Out-of-bounds Read
An out-of-bounds read occurs when software accesses memory outside the boundaries of a buffer, array, or similar data structure, reading…
CWE-130 Sibling
Improper Handling of Length Parameter Inconsistency
This vulnerability occurs when a program reads a structured data packet or message but fails to properly validate that the declared length…
CWE-466 Sibling
Return of Pointer Value Outside of Expected Range
This vulnerability occurs when a function returns a memory pointer that points outside the expected buffer range, potentially exposing…
CWE-786 Sibling
Access of Memory Location Before Start of Buffer
This vulnerability occurs when software attempts to read from or write to a memory location positioned before the official start of a…
CWE-787 Sibling
Out-of-bounds Write
This vulnerability occurs when software incorrectly writes data outside the boundaries of its allocated memory buffer, either beyond the…
CWE-788 Sibling
Access of Memory Location After End of Buffer
This vulnerability occurs when software attempts to read from or write to a memory buffer using an index or pointer that points past the…
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