In short
- CVE-2026-40879 is a HIGH (CVSS 7.5) vulnerability affecting nest (nestjs), @nestjs/microservices.
- Chance of exploitation in the next 30 days (EPSS): 0.33%, higher than 26.1% of all vulnerabilities.
- Fix: update to 11.1.19 or later.
Description
Impact
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
Patches
Fixed in @nestjs/[email protected]
References
Discovered by https://github.com/hwpark6804-gif
NVD description
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.
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