A function or operation returns an incorrect return value or status code that does not indicate the true result of execution, causing the product to modify its behavior based on the incorrect result.
View on MITREThis can lead to unpredictable behavior. If the function is used to make security-critical decisions or provide security-critical information, then the wrong status code can cause the product to assume that an action is safe or correct, even when it is not.
This weakness could place the system in a state that could lead unexpected logic to be executed or other unintended behaviors.
No mitigation information available for this CWE.
No detection method information available for this CWE.
In the following example, an HTTP 404 status code is returned in the event of an IOException encountered in a Java servlet. A 404 code is typically meant to indicate a non-existent resource and would be somewhat misleading in this case.
try { // something that might throw IOException ... } catch (IOException ioe) {response.sendError(SC_NOT_FOUND);}DNS server returns wrong response code for non-existent AAAA record, which effectively says that the domain is inaccessible.
View DetailsHardware-specific implementation of system call causes incorrect results from geteuid.
View DetailsChain: System call returns wrong value (CWE-393), leading to a resultant NULL dereference (CWE-476).
View DetailsChain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversary-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint). The code's whitespace indentation did not reflect the actual control flow (CWE-1114) and did not explicitly delimit the block (CWE-483), which could have made it more difficult for human code auditors to detect the vulnerability.
View DetailsAdditional facts reviewed against primary or authoritative security sources.
Documented detection approaches include Fuzzing; recorded impacts include Unexpected State, and Alter Execution Logic; observed examples include CVE-2003-1132, CVE-2001-1509, and CVE-2001-1559. Use these source-defined anchors to turn CWE-393 into implementation, review, and verification checks for the affected component.
CWE-393: Return of Wrong Status Code — MITRE CWEUse NIST SSDF practices to make prevention of CWE-393, Return of Wrong Status Code, an explicit development outcome. Translate the CWE definition into security requirements and design constraints, choose safer implementation patterns and toolchain checks, and define acceptance evidence before release. Feed every confirmed occurrence back into the requirements, design review, and coding rules so the same root cause is removed across the product rather than patched in one location.
NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and TechnologyUse CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-393, Return of Wrong Status Code, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.
Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security AgencyApply MITRE's full root-cause mapping guidance when using CWE-393, Return of Wrong Status Code. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.
CVE to CWE Root Cause Mapping Guidance — MITRE CWEApply MITRE's root-cause mapping quick tips to CWE-393, Return of Wrong Status Code. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.
CVE to CWE Root Cause Mapping Quick Tips — MITRE CWECWE-393: Return of Wrong Status Code is a Common Weakness Enumeration (CWE) entry maintained by MITRE. A function or operation returns an incorrect return value or status code that does not indicate the true result of execution, causing the product to modify its behavior based on the incorrect result. This can lead to unpredictable behavior. If the function is used to make security-critical decisions or provide security-critical information, then the wrong status code can cause the product to assume that an action is safe or correct, even when it is not.
If exploited, CWE-393 (Return of Wrong Status Code) it can compromise Integrity and Other, leading to outcomes such as Unexpected State and Alter Execution Logic.
CWE-393 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.
MITRE documents real CVEs mapped to CWE-393, including CVE-2003-1132, CVE-2001-1509, CVE-2001-1559 and CVE-2014-1266. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.
A CWE (Common Weakness Enumeration) like CWE-393 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.