How severe is CVE-2026-31988?

No CVSS score has been assigned to CVE-2026-31988 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-31988?

CVE-2026-31988 affects the following packages: yauzl (npm). Ecosystems affected: npm.

How do I fix CVE-2026-31988?

Update yauzl to 3.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31988 is resolved across your whole dependency graph.

How do I detect CVE-2026-31988 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yauzl. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-31988 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-31988?

O3 pinpoints whether CVE-2026-31988 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-31988 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-31988 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-31988?

CVE-2026-31988 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 38th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2026-31988 published, and has it been updated?

CVE-2026-31988 was published on March 11, 2026 and was last updated on March 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-31988: yauzl contains an off-by-one error

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk38th percentile+0.33%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

📦yauzl

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`yauzl`	≥ 3.2.0&&< 3.2.1	3.2.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yauzl. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update yauzl to 3.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31988 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-31988 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-31988. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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 p

O3 Security · Impact-Aware SCA

Is CVE-2026-31988 in your dependencies?

O3 detects CVE-2026-31988 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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CVE-2026-31988