Summary
yauzl (aka Yet Another Unzip Library) version 3.2.0 for Node.js contains an off-by-one error in the NTFS extended timestamp extra field parser within the getLastModDate() function. The while loop condition checks cursor < data.length + 4 instead of cursor + 4 <= data.length, allowing readUInt16LE() to read past the buffer boundary. A remote attacker can cause a denial of service (process crash via ERR_OUT_OF_RANGE exception) by sending a crafted zip file with a malformed NTFS extra field. This affects any Node.js application that processes zip file uploads and calls entry.getLastModDate() on parsed entries. Fixed in version 3.2.1.
Impact
CVE-2026-31988 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no 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 (3.2.1); 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.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-31988? CVE-2026-31988 is a medium-severity security vulnerability in yauzl (npm), affecting versions = 3.2.0. It is fixed in 3.2.1.
- How severe is CVE-2026-31988? CVE-2026-31988 has a CVSS score of 5.3 (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 yauzl are affected by CVE-2026-31988? yauzl (npm) versions = 3.2.0 is affected.
- Is there a fix for CVE-2026-31988? Yes. CVE-2026-31988 is fixed in 3.2.1. Upgrade to this version or later.
- Is CVE-2026-31988 exploitable, and should I be worried? Whether CVE-2026-31988 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-2026-31988 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-2026-31988? Upgrade
yauzlto 3.2.1 or later.