CWE-324: Use of a Key Past its Expiration Date

Extended Description

While the expiration of keys does not necessarily ensure that they are compromised, it is a significant concern that keys which remain in use for prolonged periods of time have a decreasing probability of integrity. For this reason, it is important to replace keys within a period of time proportional to their strength.

Code Examples & CVEs

Demonstrative Examples

The following code attempts to verify that a certificate is valid.

The code checks if the certificate is not yet valid, but it fails to check if a certificate is past its expiration date, thus treating expired certificates as valid.

BadC

if (cert = SSL_get_peer_certificate(ssl)) {                         foo=SSL_get_verify_result(ssl);if ((X509_V_OK==foo) || (X509_V_ERRCERT_NOT_YET_VALID==foo))                                                                                                   //do stuff                                                                                                                                            }

Observed CVE Examples (1)

CVE-2021-33020

Picture Archiving and Communication System (PACS) system for hospitals uses a cryptographic key or password past its expiration date

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-324 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-324, Use of a Key Past its Expiration Date, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Use of a Key Past its Expiration Date during Architecture and Design

MITRE associates mitigation with Architecture and Design; recorded impacts include Bypass Protection Mechanism, and Gain Privileges or Assume Identity; observed examples include CVE-2021-33020. Use these source-defined anchors to turn CWE-324 into implementation, review, and verification checks for the affected component.

CWE-324: Use of a Key Past its Expiration Date — MITRE CWE

Triage CWE-324 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-324, Use of a Key Past its Expiration Date, 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 Agency

Apply precise root-cause mapping to CWE-324

Apply MITRE's full root-cause mapping guidance when using CWE-324, Use of a Key Past its Expiration Date. 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 CWE

Validate CWE-324 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-324, Use of a Key Past its Expiration Date. 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 CWE

Frequently Asked Questions

What is CWE-324: Use of a Key Past its Expiration Date?+

CWE-324: Use of a Key Past its Expiration Date is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product uses a cryptographic key or password past its expiration date, which diminishes its safety significantly by increasing the timing window for cracking attacks against that key. While the expiration of keys does not necessarily ensure that they are compromised, it is a significant concern that keys which remain in use for prolonged periods of time have a decreasing probability of integrity. For this reason, it is important to replace keys within a period of time proportional to their strength.

What are the security consequences of Use of a Key Past its Expiration Date?+

If exploited, CWE-324 (Use of a Key Past its Expiration Date) it can compromise Access Control, leading to outcomes such as Bypass Protection Mechanism and Gain Privileges or Assume Identity.

How do you prevent or mitigate Use of a Key Past its Expiration Date?+

Recommended mitigations for CWE-324 include: Adequate consideration should be put in to the user interface in order to notify users previous to the key's expiration, to explain the importance of new key generation and to walk users through the process as painlessly as possible.

Which programming languages are affected by Use of a Key Past its Expiration Date?+

CWE-324 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Use of a Key Past its Expiration Date?+

MITRE documents real CVEs mapped to CWE-324, including CVE-2021-33020. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-324 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.

CWE-324: Use of a Key Past its Expiration Date

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