Summary
cookie-signature Timing Attack
Affected versions of cookie-signature are vulnerable to timing attacks as a result of using 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 charset*length guesses, instead of charset^length guesses required were the timing attack not present.
Impact
Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.
CVE-2016-1000236 has a CVSS score of 4.4 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.0.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Update to 1.0.4 or later.
Frequently Asked Questions
- What is CVE-2016-1000236? CVE-2016-1000236 is a medium-severity race condition vulnerability in cookie-signature (npm), affecting versions < 1.0.4. It is fixed in 1.0.4. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
- How severe is CVE-2016-1000236? CVE-2016-1000236 has a CVSS score of 4.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of cookie-signature are affected by CVE-2016-1000236? cookie-signature (npm) versions < 1.0.4 is affected.
- Is there a fix for CVE-2016-1000236? Yes. CVE-2016-1000236 is fixed in 1.0.4. Upgrade to this version or later.
- Is CVE-2016-1000236 exploitable, and should I be worried? Whether CVE-2016-1000236 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2016-1000236 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2016-1000236? Upgrade
cookie-signatureto 1.0.4 or later.