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GHSA-6wvw-vrw4-363w
node-opcuaSummary 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/server_secure_channel_layer.ts at line 156, g_alreadyUsedNonce 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 reliable heap exhaustion across repeated connection cycles.
Measured Impact
Dynamically confirmed heap growth:
- 5,000 unique nonces → +1.23 MB resident heap, no eviction after explicit GC
- Projected: 10^6 nonces → ~246 MB resident heap
- Achievable OOM on default Node.js heap limits
Suggested Fix
Add a TTL-based eviction policy to g_alreadyUsedNonce. Nonces should be expired after the maximum session timeout (or a reasonable fixed window, e.g. 1 hour). A Map with timestamp entries and periodic cleanup is sufficient.
I am following a 90-day responsible disclosure policy. I am happy to provide additional technical details under embargo. Please confirm receipt at your earliest convenience.
Reporter: Stanley Tobias Discovery date: 2026-03-23
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The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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