Vulnerability in Nestjs Nest

CVE-2026-40879

Nest is a framework for building scalable Node.js server-side applications. Prior to 11.1.19, when an attacker sends many small, valid JSON messages in one TCP frame, handleData() recurses once per message; the buffer shrinks each call. maxBufferSize is never reached; call stack overflows instead. A ~47 KB payload is sufficient to trigger RangeError. This vulnerability is fixed in 11.1.19.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.003 (25.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-40879: held from 0.005 to 0.003.

EPSS over last 30 days · oldest: 0.005 · newest: 0.003 · change: -0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-40879?
CVE-2026-40879 is a high-severity vulnerability in Nestjs Nest, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-04-21.
How severe is CVE-2026-40879?
High severity. CVSS v3 base score is 7.5 out of 10.