CWE-115 Base Incomplete

Misinterpretation of Input

This vulnerability occurs when software incorrectly interprets or processes input data, leading to unintended and potentially harmful security consequences. The flawed interpretation can come from…

Definition

What is CWE-115?

This vulnerability occurs when software incorrectly interprets or processes input data, leading to unintended and potentially harmful security consequences. The flawed interpretation can come from user-provided data, external systems, or other components.
At its core, this weakness is about a mismatch between what the software expects and how it actually handles incoming information. Instead of rejecting malformed data or processing it safely, the system assigns it the wrong meaning or context. This misinterpretation then ripples through the application logic, creating openings for attackers to manipulate behavior, bypass checks, or corrupt data. Common triggers include incorrect character encoding handling, flawed protocol parsing, or mistaken assumptions about data structure or boundaries. For developers, prevention starts with adopting a strict and consistent parsing strategy. Always validate and sanitize all input against a well-defined schema before processing. Use established libraries for complex formats (like XML, JSON, or network protocols) rather than custom parsers. Implement clear data transformation pipelines and log parsing decisions to catch discrepancies early. Assume input is malicious until proven otherwise, and design your data handling to fail securely—defaulting to a denied state when interpretation fails.
Real-world impact

Real-world CVEs caused by CWE-115

  • Product sees dangerous file extension in free text of a group discussion, disconnects all users.

  • Product does not correctly import and process security settings from another product.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 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.

Vulnerable pseudo
// 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

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-115

  • 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-115

Fuzzing High

Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

CWE-115

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

Frequently asked questions

What is CWE-115?

This vulnerability occurs when software incorrectly interprets or processes input data, leading to unintended and potentially harmful security consequences. The flawed interpretation can come from user-provided data, external systems, or other components.

How serious is CWE-115?

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-115?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-115?

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-115?

Plexicus's SAST engine matches the data-flow signature for CWE-115 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-115?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/115.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-115

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SAMPLE HANDOVER · ILLUSTRATIVE

Sample evidence handover

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VALIDATED FINDING Evidence attached

Server-Side Request Forgery in webhooks/receiver

demo-project/sample-app · src/webhooks/receiver.py:42

SeverityHigh CVSS 3.18.6 Priority79 Confirmedvia replay

Untrusted caller-supplied URLs reach an internal egress without an allowlist. Replayed in a sandbox against a fresh authorised target — the same control was validated to fail twice.

REVIEWER-READY REMEDIATION Merge-ready PR

Validate the target URL against an allowlist of permitted hostnames. Reject private/internal IP ranges. Enforce HTTPS only.

plexicus/remediation/webhooks-ssrf 3 changed · 0 new files
42resp = requests.get(target_url)
42+if not is_allowed_host(target_url):
43+  raise WebhookRejected(target_url)
44+resp = requests.get(target_url, timeout=5)
Every engagement hands over:
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  • Validated findings list
  • Merge-ready PRs
  • Compliance mapping (NIS2 · DORA · CRA)