EUVD-2026-77624
GHSA-6wvw-vrw4-363w
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Unauthenticated network path with no complexity barrier; impact is purely availability loss from heap exhaustion with no confidentiality or integrity exposure.
Primary rating from Vendor (https://github.com/node-opcua/node-opcua).
CVSS VectorVendor: https://github.com/node-opcua/node-opcua
Lifecycle Timeline
3Blast Radius
ecosystem impact- 2 npm packages depend on node-opcua (2 direct, 0 indirect)
Ecosystem-wide dependent count for version 2.166.0.
DescriptionCVE.org
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
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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.
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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
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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.
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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
AnalysisAI
Heap exhaustion denial-of-service in the node-opcua npm library (versions ≤ 2.165.0) allows an unauthenticated remote attacker to crash the server process by repeatedly initiating OPC-UA sessions with unique nonces. The root cause is a process-global nonce cache (g_alreadyUsedNonce) that accumulates entries indefinitely with no TTL or eviction, causing unbounded heap growth measurable at approximately 1.23 MB per 5,000 nonces - achievable OOM under default Node.js heap limits. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | No special conditions are required beyond TCP network access to the OPC-UA server port. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) is internally consistent and accurately reflects the attack surface: zero prerequisites beyond network reachability, no authentication, no complexity barrier, with complete availability loss as the sole impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade node-opcua to version 2.168.0 or later, available at https://github.com/node-opcua/node-opcua/releases/tag/v2.168.0. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all node-opcua deployments at version 2.165.0 or earlier and immediately restrict OPC-UA network access to trusted hosts via firewall rules; simultaneously enable per-IP session rate limiting to constrain attack impact. …
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External POC / Exploit Code
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