Summary
Out-of-bounds Read in base64-url
Versions of base64-url before 2.0.0 are vulnerable to out-of-bounds read as it allocates uninitialized Buffers when number is passed in input.
Impact
A read operation accesses a memory location beyond the intended buffer boundary. Typical impact: sensitive data disclosure or crash.
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 version 2.0.0 or later.
Frequently Asked Questions
- What is GHSA-J4MR-9XW3-C9JX? GHSA-J4MR-9XW3-C9JX is a high-severity out-of-bounds read vulnerability in base64-url (npm), affecting versions < 2.0.0. It is fixed in 2.0.0. A read operation accesses a memory location beyond the intended buffer boundary.
- Which versions of base64-url are affected by GHSA-J4MR-9XW3-C9JX? base64-url (npm) versions < 2.0.0 is affected.
- Is there a fix for GHSA-J4MR-9XW3-C9JX? Yes. GHSA-J4MR-9XW3-C9JX is fixed in 2.0.0. Upgrade to this version or later.
- Is GHSA-J4MR-9XW3-C9JX exploitable, and should I be worried? Whether GHSA-J4MR-9XW3-C9JX 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 GHSA-J4MR-9XW3-C9JX 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 GHSA-J4MR-9XW3-C9JX? Upgrade
base64-urlto 2.0.0 or later.