The product uses a scheme that generates numbers or identifiers that are more predictable than required.
View on MITRENo mitigation information available for this CWE.
No detection method information available for this CWE.
This code generates a unique random identifier for a user's session.
Because the seed for the PRNG is always the user's ID, the session ID will always be the same. An attacker could thus predict any user's session ID and potentially hijack the session.
function generateSessionID($userID){srand($userID);return rand();}Product for administering PBX systems uses predictable identifiers and timestamps for filenames (CWE-340) which allows attackers to access files via direct request (CWE-425).
View DetailsPRNG allows attackers to use the output of small PRNG requests to determine the internal state information, which could be used by attackers to predict future pseudo-random numbers.
View DetailsAdditional facts reviewed against primary or authoritative security sources.
Documented detection approaches include Automated Static Analysis; recorded impacts include Varies by Context; observed examples include CVE-2022-29330, CVE-2001-1141, and CVE-1999-0074. Use these source-defined anchors to turn CWE-340 into implementation, review, and verification checks for the affected component.
CWE-340: Generation of Predictable Numbers or Identifiers — MITRE CWEUse NIST SSDF practices to make prevention of CWE-340, Generation of Predictable Numbers or Identifiers, 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-340, Generation of Predictable Numbers or Identifiers, 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-340, Generation of Predictable Numbers or Identifiers. 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-340, Generation of Predictable Numbers or Identifiers. 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-340: Generation of Predictable Numbers or Identifiers is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product uses a scheme that generates numbers or identifiers that are more predictable than required.
If exploited, CWE-340 (Generation of Predictable Numbers or Identifiers) it can compromise Other, leading to outcomes such as Varies by Context.
CWE-340 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-340, including CVE-2022-29330, CVE-2001-1141 and CVE-1999-0074. 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-340 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.