Vulnerability · Published Sep 14, 2026 · Assigned by GitHub_M

CVE-2026-54156node-opcua: Unbounded nonce cache enables unauthenticated heap exhaustion DoS

High 7.5

In plain English

A high-severity resource allocation without limits in node-opcua from node-opcua. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 56% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.8%top 43.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	node-opcua	2.166.0	GHSA-6wvw-vrw4-363w

Affected products (as reported)

Vendor	Product	Versions
node-opcua	node-opcua	< 2.166.0

Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/node-opcua/node-opcua/security/advisories/GHSA-6wvw-vrw4-363w x_refsource_CONFIRM
https://github.com/node-opcua/node-opcua/commit/b82c2939fe9c658de58da993f2798ec5481d7313 x_refsource_MISC
https://github.com/node-opcua/node-opcua/releases/tag/v2.166.0 x_refsource_MISC