# CVE-2026-54156

## Summary

- **CVE ID:** CVE-2026-54156
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** CWE-770
- **Published:** Sep 14, 2026
- **Last Modified:** Sep 14, 2026

## Description

node-opcua is an OPC UA implementation for TypeScript and Node.js. Prior to 2.166.0, the process-global g_alreadyUsedNonce cache used by nonceAlreadyBeenUsed in packages/node-opcua-secure-channel/source/server/server_secure_channel_layer.ts records nonces from OpenSecureChannelRequest and CreateSession without expiration or a size limit. An unauthenticated remote attacker can repeatedly create sessions with unique nonces, causing entries to persist after session expiry and accumulate across connection cycles even when maxSessions=10 limits concurrent sessions. The resulting unbounded heap growth can exhaust the default Node.js heap and crash the node-opcua server process. This issue is fixed in version 2.166.0.

## Affected Products

- node-opcua — node-opcua (< 2.166.0)

## References

- [CNA](https://github.com/node-opcua/node-opcua/security/advisories/GHSA-6wvw-vrw4-363w)
- [CNA](https://github.com/node-opcua/node-opcua/commit/b82c2939fe9c658de58da993f2798ec5481d7313)
- [CNA](https://github.com/node-opcua/node-opcua/releases/tag/v2.166.0)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.55%
- **EPSS Percentile:** 44.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._