EUVD-2026-30543
GHSA-58qx-3vcg-4xpx
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Network-reachable and unauthenticated, but AC:H because it requires the app to use a TypedArray close reason, and C:L since only opportunistic uninitialized heap leaks.
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Lifecycle Timeline
10Blast Radius
ecosystem impact- 31 npm packages depend on ws (21 direct, 11 indirect)
Ecosystem-wide dependent count for version 8.0.0.
DescriptionNVD
ws is an open source WebSocket client and server for Node.js. Prior to 8.20.1, the websocket.close() implementation is vulnerable to uninitialized memory disclosure when a TypedArray is passed as the reason argument. This vulnerability is fixed in 8.20.1.
AnalysisAI
Uninitialized memory disclosure in the ws WebSocket library for Node.js (versions 8.0.0 through 8.20.0) allows a connected peer to receive leaked process memory when an application calls websocket.close() with a TypedArray as the reason argument. Because the close-frame reason buffer is not zero-initialized, fragments of adjacent heap memory - potentially containing secrets, tokens, or other clients' data - are transmitted over the wire. No public exploit is identified at time of analysis (SSVC lists POC-class maturity but EPSS is only 0.01%), and the issue is fixed in ws 8.20.1.
Technical ContextAI
ws is one of the most widely used WebSocket client/server implementations in the Node.js ecosystem, shipped as a transitive dependency of countless frameworks (Socket.IO, express-ws, etc.). The flaw is rooted in CWE-908 (Use of Uninitialized Resource): when websocket.close(code, reason) is invoked with a TypedArray reason, ws allocates a buffer for the close-frame payload without fully initializing it, so previously-freed or never-written heap bytes are copied into the outbound frame. The affected component is identified by CPE cpe:2.3:a:ws_project:ws for the node.js target. The control frame's reason field is then sent to the remote peer per RFC 6455, turning an internal memory-handling bug into a network-observable information leak.
RemediationAI
Vendor-released patch: ws 8.20.1 - upgrade the ws dependency (including transitive copies pulled in by frameworks such as Socket.IO) to 8.20.1 or later, then audit your lockfile to ensure no nested older copies remain. Red Hat consumers should apply the corresponding errata (RHSA-2026:7655, RHSA-2026:26638, RHSA-2026:26994, RHSA-2026:27171, RHSA-2026:29197) via the platform package manager; see https://access.redhat.com/errata/RHSA-2026:29197 and the advisory at https://github.com/websockets/ws/security/advisories/GHSA-58qx-3vcg-4xpx. If you cannot upgrade immediately, a targeted compensating control is to ensure application code never passes a TypedArray (e.g., Uint8Array) to websocket.close() - instead pass the reason as a string or omit it - which avoids the vulnerable allocation path entirely; the trade-off is a code change in every place that closes a socket with a binary reason, but it has no protocol-level side effects since string reasons are fully supported by RFC 6455. The upstream fix commit is https://github.com/websockets/ws/commit/c0327ec15a54d701eb6ccefaa8bef328cfc03086.
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Same weakness CWE-908 – Use of Uninitialized Resource
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