CVE-2026-40879: Nest Affected by DoS via Recursive handleData in JsonSocket (TCP Transport)

April 14, 2026 (updated April 15, 2026)

Attacker sends many small, valid JSON messages in one TCP frame → handleData() recurses once per message; buffer shrinks each call → maxBufferSize is never reached; call stack overflows instead → A ~47 KB payload is sufficient to trigger RangeError

References

github.com/advisories/GHSA-hpwf-8g29-85qm
github.com/nestjs/nest
github.com/nestjs/nest/security/advisories/GHSA-hpwf-8g29-85qm
nvd.nist.gov/vuln/detail/CVE-2026-40879

Code Behaviors & Features

Detect and mitigate CVE-2026-40879 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Learn more about Dependency Scanning →