CWE-323: Reusing a Nonce, Key Pair in Encryption

Code Examples & CVEs

Demonstrative Examples

This code takes a password, concatenates it with a nonce, then encrypts it before sending over a network:

Because the nonce used is always the same, an attacker can impersonate a trusted party by intercepting and resending the encrypted password. This attack avoids the need to learn the unencrypted password.

BadC

void encryptAndSendPassword(char *password){char *nonce = "bad";...char *data = (unsigned char*)malloc(20);int para_size = strlen(nonce) + strlen(password);char *paragraph = (char*)malloc(para_size);SHA1((const unsigned char*)paragraph,parsize,(unsigned char*)data);sendEncryptedData(data)}

This code sends a command to a remote server, using an encrypted password and nonce to prove the command is from a trusted party:

Once again the nonce used is always the same. An attacker may be able to replay previous legitimate commands or execute new arbitrary commands.

BadC++

String command = new String("some command to execute");MessageDigest nonce = MessageDigest.getInstance("SHA");nonce.update(String.valueOf("bad nonce"));byte[] nonce = nonce.digest();MessageDigest password = MessageDigest.getInstance("SHA");password.update(nonce + "secretPassword");byte[] digest = password.digest();sendCommand(digest, command)

Observed CVE Examples (2)

CVE-2024-36289

social networking app reuses a nonce/key pair, allowing MITM attackers to manipulate direct messages

View Details

CVE-2024-21530

Rust package reuses a nonce/key pair when an object is cloned, which resets the random number generation

View Details

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-323 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-323, Reusing a Nonce, Key Pair in Encryption, 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 Reusing a Nonce, Key Pair in Encryption during Implementation

MITRE associates mitigation with Implementation; documented detection approaches include Automated Static Analysis; recorded impacts include Bypass Protection Mechanism, and Gain Privileges or Assume Identity. Use these source-defined anchors to turn CWE-323 into implementation, review, and verification checks for the affected component.

CWE-323: Reusing a Nonce, Key Pair in Encryption — MITRE CWE

Triage CWE-323 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-323, Reusing a Nonce, Key Pair in Encryption, 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-323

Apply MITRE's full root-cause mapping guidance when using CWE-323, Reusing a Nonce, Key Pair in Encryption. 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-323 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-323, Reusing a Nonce, Key Pair in Encryption. 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-323: Reusing a Nonce, Key Pair in Encryption?+

CWE-323: Reusing a Nonce, Key Pair in Encryption is a Common Weakness Enumeration (CWE) entry maintained by MITRE. Nonces should be used for the present occasion and only once.

What are the security consequences of Reusing a Nonce, Key Pair in Encryption?+

If exploited, CWE-323 (Reusing a Nonce, Key Pair in Encryption) 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 Reusing a Nonce, Key Pair in Encryption?+

Recommended mitigations for CWE-323 include: Refuse to reuse nonce values. Use techniques such as requiring incrementing, time based and/or challenge response to assure uniqueness of nonces.

Which programming languages are affected by Reusing a Nonce, Key Pair in Encryption?+

CWE-323 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 Reusing a Nonce, Key Pair in Encryption?+

MITRE documents real CVEs mapped to CWE-323, including CVE-2024-36289 and CVE-2024-21530. 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-323 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-323: Reusing a Nonce, Key Pair in Encryption

Technical Details

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Mitigation Strategies

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Description