node-opcua: TCP Socket Leak (FIN-WAIT-2) via keepalive reconnection cycle - Resource Exhaustion

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

node-opcua is an OPC UA implementation for TypeScript and Node.js. From 2.0.0 until 2.170.0, node-opcua clients using the default keepSessionAlive setting can enter a repeated reconnection cycle when an OPC UA server's clock skew causes BadInvalidTimestamp responses. ClientSessionKeepAliveManager._ping_server treated the server-originated ServiceFault as a network outage and forced a transport reconnect, while ClientTCP_transport._on_ACK_response used socket.end() after failed HEL/ACK negotiation and could leave the connection in FIN-WAIT-2 when the peer did not close. Repetition at the keepAliveInterval accumulates file descriptors and memory until the client process or container can be terminated by resource exhaustion. This issue is fixed in version 2.170.0.

Source published

16 Sep 2026 16:18:28 UTC

Source modified

16 Sep 2026 18:34:50 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 7.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

node-opcua is an OPC UA implementation for TypeScript and Node.js. From 2.0.0 until 2.170.0, node-opcua clients using the default keepSessionAlive setting can enter a repeated reconnection cycle when an OPC UA server's clock skew causes BadInvalidTimestamp responses. ClientSessionKeepAliveManager._ping_server treated the server-originated ServiceFault as a network outage and forced a transport reconnect, while ClientTCP_transport._on_ACK_response used socket.end() after failed HEL/ACK negotiation and could leave the connection in FIN-WAIT-2 when the peer did not close. Repetition at the keepAliveInterval accumulates file descriptors and memory until the client process or container can be terminated by resource exhaustion. This issue is fixed in version 2.170.0.

Source published

Sep 16, 2026, 4:18:28 PM (timezone not stated)

Source modified

Sep 16, 2026, 6:34:50 PM (timezone not stated)

Observed here

11 Nov 2026 15:59:59 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 7.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

node-opcua is an OPC UA implementation for TypeScript and Node.js. From 2.0.0 until 2.170.0, node-opcua clients using the default keepSessionAlive setting can enter a repeated reconnection cycle when an OPC UA server's clock skew causes BadInvalidTimestamp responses. ClientSessionKeepAliveManager._ping_server treated the server-originated ServiceFault as a network outage and forced a transport reconnect, while ClientTCP_transport._on_ACK_response used socket.end() after failed HEL/ACK negotiation and could leave the connection in FIN-WAIT-2 when the peer did not close. Repetition at the keepAliveInterval accumulates file descriptors and memory until the client process or container can be terminated by resource exhaustion. This issue is fixed in version 2.170.0.

Source published

16 Sep 2026 17:18:00 UTC

Source modified

30 Sep 2026 17:51:36 UTC

Observed here

25 Oct 2026 15:18:51 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

SUMMARY ------- A combination of bugs in node-opcua causes unlimited TCP socket accumulation (FIN-WAIT-2 state) during automatic reconnection, leading to memory exhaustion and eventual container/process crash (OOM kill). The issue is triggered by the default configuration (keepSessionAlive: true) when the OPC UA server has clock skew relative to the client. Affected version: Tested on 2.169.0 (latest as of April 2026). ENVIRONMENT ----------- - Node.js: v24.11.0 - node-opcua: 2.169.0 - OS: Linux (containerized via Podman, slirp4netns networking) - OPC UA Server: Industrial PLC (opc.tcp endpoint), clock skew of ~50 minutes ahead of client - Client config: keepSessionAlive: true (default), keepAliveInterval: 3000, securityMode: None, securityPolicy: None ROOT CAUSE ANALYSIS ------------------- Bug #1 - ClientTCP_transport._on_ACK_response() uses socket.end() instead of socket.destroy() File: node-opcua-transport/src/client_tcp_transport.ts, _on_ACK_response() method When the HEL/ACK handshake fails during a reconnection attempt, the error handler calls socket.end(): if (err || !data) { externalCallback(err || new Error("no data")); if (this._socket) { this._socket.end(); // <- sends TCP FIN, leaves socket in FIN-WAIT-2 } } socket.end() sends a TCP FIN and waits for the peer to close its side. If the peer doesn't respond (common with PLCs), the socket remains in FIN-WAIT-2 state indefinitely, leaking file descriptors and memory. During rapid reconnection cycles (triggered by Bug #2 below), every failed HEL/ACK creates a new leaked socket. --- Bug #2 - ClientSessionKeepAliveManager._ping_server() treats BadInvalidTimestamp as network outage File: node-opcua-client/src/client_session_keepalive_manager.ts, _ping_server() method The keepalive manager reads Server.ServerStatus.CurrentTime on each ping cycle. If the server responds with BadInvalidTimestamp (because the client's RequestHeader.timestamp falls outside the server's tolerance window due to clock skew), the manager treats this as a fatal network error: // Any error -> emit("failure") -> terminateConnection() -> forceConnectionBreak() This triggers a full transport-level reconnection on every keepalive cycle (every keepAliveInterval ms). Combined with Bug #1, each reconnection attempt leaks one TCP socket in FIN-WAIT-2. Impact amplification: With keepAliveInterval: 3000 (3 seconds), the client leaks ~20 sockets/minute, ~1200/hour, exhausting resources in hours. REPRODUCTION STEPS ------------------ 1. Set up an OPC UA server with a clock skewed more than the server's timestamp tolerance ahead of the client. 2. Connect using node-opcua with default settings (keepSessionAlive: true). 3. Monitor TCP sockets: ss -antp | grep FIN-WAIT-2 | wc -l 4. Observe FIN-WAIT-2 count growing continuously (approximately one per keepalive interval). 5. Eventually the process runs out of file descriptors or memory and crashes. SUGGESTED FIXES --------------- For Bug #1 (_on_ACK_response): // Replace socket.end() with socket.destroy() if (this._socket) { this._socket.destroy(); } For Bug #2 (_ping_server): Distinguish between transport-level errors (actual network outage) and application-level OPC UA status codes like BadInvalidTimestamp. The latter indicates the server is reachable and the session is alive - only the timestamp validation failed. The keepalive should not trigger reconnection. REPORTER -------- Marco Velluso @Velluso [[email protected]](mailto:[email protected]) Requesting CVE assignment and credit as reporter upon fix publication.

Source published

16 Sep 2026 16:19:21 UTC

Source modified

16 Sep 2026 16:30:30 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

Publisher rating · HIGH