Socket.IO: Engine.IO Protocol Revision Mismatch DoS

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-102599
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-13 19:17:49 UTC
Updated2026-10-13 19:25:38 UTC
DescriptionSocket.IO enables bidirectional and low-latency communication for every platform. From Engine.IO 6.6.0 until 6.6.10, a transport upgrade can independently derive an Engine.IO protocol revision from the upgrade request instead of enforcing the revision stored on the existing session. A malicious client can establish a valid session and send an upgrade request with a different or omitted EIO query parameter, attaching a transport with incompatible parser and heartbeat behavior. A crafted heartbeat packet can then trigger an uncaught exception and terminate the Node.js process, including when Engine.IO v3 compatibility is disabled because an omitted EIO value is interpreted as revision 3 on the affected path. This issue is fixed in Engine.IO 6.6.10.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

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

Problem Types: CWE-248 | CWE-248 CWE-248: Uncaught Exception

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Socketio Socket.io affected >= 6.6.0, < 6.6.10 Not specified

References

ReferenceSourceLinkTags
github.com/socketio/socket.io/security/advisories/GHSA-2gc4-cqfq-p2gv [email protected] github.com
github.com/socketio/socket.io/commit/86db1fc3db2cd315a065d64c4e48918ccf9... [email protected] github.com
github.com/socketio/socket.io/releases/tag/[email protected] [email protected] github.com
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