Severity: high

Timing Attack



Affected versions of csrf-lite are vulnerable to timing attacks as a result of testing CSRF tokens via a fail-early comparison instead of a constant-time comparison.

Timing attacks remove the exponential increase in entropy gained from increased secret length, by providing per-character feedback on the correctness of a guess via miniscule timing differences.

Under favorable network conditions, an attacker can exploit this to guess the secret in no more than (16*18)288 guesses, instead of the 16^18 guesses required were the timing attack not present.


Update to version 0.1.2 or later.


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Advisory timeline

  1. published

    Advisory published
    Apr 23rd, 2016
  2. reported

    Initial report by Todd Wolfson
    Mar 28th, 2016