Description

An issue was identified in which CSRF tokens were generated using a predictable method, potentially reducing their effectiveness as a security control. This has been addressed by improving the randomness and entropy of token generation.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.3",
  "pubDate": "2026-08-14T18:17:22.953Z",
  "pubdate": "2026-08-14T18:17:22.953Z",
  "executiveSummary": "An issue was identified in the application involving Cross-Site Request Forgery (CSRF) protection mechanisms, specifically related to the cryptographic entropy and predictability of generated anti-CSRF tokens. Due to an insufficient random number generation methodology, the tokens lack adequate unpredictability, reducing their overall efficacy as a defensive security control against unauthorized state-changing operations.\nThe vulnerability introduces significant risk implications, as an attacker capable of observing or analyzing previously issued tokens may derive an algorithmically predictable pattern. This diminishes the intended security boundary of the CSRF mitigation implementation.\nAttacker capabilities in this scenario include the potential ability to forecast subsequent valid CSRF tokens or deduce valid tokens through computational analysis. Successful exploitation enables unauthorized third-party actors to forge state-changing HTTP requests on behalf of authenticated users, potentially leading to unauthorized data modification, account compromise, or administrative action execution.\nAlthough specific product names, version numbers, CVE IDs, or CWE IDs were not provided in the source description, the vulnerability fundamentally stems from weak cryptographic pseudorandom number generators (PRNG) or deterministic seeding patterns within the token generation routine. Remediation requires modernizing the token generation subsystem to utilize cryptographically secure pseudo-random number generators (CSPRNG) with high entropy.",
  "technicalDetails": "The root cause of this vulnerability lies in the implementation of the token generation mechanism, which utilized a predictable method rather than a cryptographically secure entropy source. In secure web application architectures, anti-CSRF tokens must be generated using a Cryptographically Secure Pseudo-Random Number Generator (CSPRNG) to ensure that output values cannot be guessed, computed, or reverse-engineered by observing a sequence of historical values.\nWhen a token generation algorithm relies on predictable primitives—such as standard linear congruential generators, time-dependent seeding without sufficient entropy, or non-cryptographic hash functions—the internal state of the PRNG may be compromised. This allows an attacker to analyze a subset of intercepted or harvested tokens to predict future tokens or narrow down the search space significantly.\nThe step-by-step attack flow typically proceeds as follows: First, an attacker observes or acquires one or more valid CSRF tokens issued to a user session or multiple sessions. Second, the attacker analyzes the token sequence to identify patterns, timestamps, or predictable components resulting from the weak generation algorithm. Third, using this computational derivation, the attacker forecasts a valid CSRF token destined to be associated with a target victim's session or constructs a valid forged token.\nFourth, the attacker crafts a malicious external website or payload containing an automated cross-origin request (such as a forged form submission or XMLHttpRequest) incorporating the predicted or derived CSRF token. Finally, when the authenticated victim visits the attacker-controlled resource, the browser automatically dispatches the request along with the victim's session cookies and the forged token to the vulnerable target application. Because the token satisfies the predictable validation check, the application processes the state-changing request as legitimate.\nThe vulnerable component is the specific function, module, or library responsible for generating and validating anti-CSRF tokens. The exploitation of this flaw does not inherently require complex pre-authentication privileges beyond the ability to interact with the application and harvest or observe token outputs, depending on whether tokens are exposed via headers, cookies, or DOM elements. Network exposure encompasses any interface where state-changing actions are protected by the weakened CSRF mechanism."
}