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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-54156: 0.78% estimated exploitation activity in the next 30 days; percentile 56.10 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A process-global nonce cache with no eviction policy allows an unauthenticated remote attacker to exhaust server heap memory by repeatedly opening sessions, causing the node-opcua server process to crash. Affected versions: <= 2.165.0 Tested version: 2.165.0 CVSS Score: 7.5 (High) CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CWE: CWE-770 Allocation of Resources Without Limits or Throttling --- Root Cause In packages/node-opcua-secure-channel/source/server/serversecurechannellayer.ts at line 156, galreadyUsedNonce is a process-global object used to track previously seen nonces for replay detection. Entries are added on every OpenSecureChannelRequest and every CreateSession request but are never removed or expired. An unauthenticated attacker can exploit the CreateSession path (which requires no certificate) to accumulate nonce entries indefinitely. Even with maxSessions=10 limiting concurrent sessions, nonces persist after session expiry, allowing slow but…

Published by the source

20 Aug 2026, 18:35 UTC

Last modified by the source

27 Aug 2026, 19:04 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-6wvw-vrw4-363w

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# Patch Next advisory brief: CVE-2026-54156

Advisory: node-opcua: Unbounded nonce cache enables unauthenticated heap exhaustion DoS
IDs: CVE-2026-54156, GHSA-6wvw-vrw4-363w
Record: https://patchnext.com/advisories/cve-2026-54156 (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: node-opcua 2.166.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm node-opcua: affected < 2.166.0; fixed in 2.166.0

## Suggested inspection (read-only)
- `npm ls node-opcua --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on node-opcua.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-6wvw-vrw4-363w (GitHub-reviewed advisory GHSA-6wvw-vrw4-363w lists affected ranges: npm node-opcua >=0 <2.166.0)

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