ws before 8.21.1 contains a memory exhaustion vulnerability in lib/receiver.js where the fragment guard only triggers when fragment count reaches maxFragments, allowing attackers to exhaust memory by sending incomplete fragmented WebSocket messages. Attackers can send a text frame with FIN=0 followed by continuation frames without completing the sequence, causing each fragment to be stored as a separate Buffer object with significant overhead, enabling denial of service through heap exhaustion.

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.0045.

Exploitation none

Automatable yes

Technical Impact partial

Affected Vendors & Products

Vendors Products
Websockets Subscribe
Ws Subscribe

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Ws Subscribe
Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References

No reference.

History

Wed, 29 Jul 2026 18:30:00 +0000

Type Values Removed Values Added
Title ws < 8.21.1 Default maxFragments Allows Memory Exhaustion DoS
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 29 Jul 2026 17:45:00 +0000

Type Values Removed Values Added
Description ws before 8.21.1 contains a memory exhaustion vulnerability in lib/receiver.js where the fragment guard only triggers when fragment count reaches maxFragments, allowing attackers to exhaust memory by sending incomplete fragmented WebSocket messages. Attackers can send a text frame with FIN=0 followed by continuation frames without completing the sequence, causing each fragment to be stored as a separate Buffer object with significant overhead, enabling denial of service through heap exhaustion. This CVE ID has been rejected or withdrawn by its CVE Numbering Authority as a duplicate of CVE-2026-48779.
Weaknesses CWE-770
CPEs cpe:2.3:a:websockets_project:websockets:*:*:*:*:*:python:*:*
Vendors & Products Websockets Project
Websockets Project websockets
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Tue, 28 Jul 2026 02:30:00 +0000

Type Values Removed Values Added
First Time appeared Websockets Project
Websockets Project websockets
CPEs cpe:2.3:a:websockets_project:websockets:*:*:*:*:*:python:*:*
Vendors & Products Websockets Project
Websockets Project websockets

Thu, 16 Jul 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Websockets
Websockets ws
Vendors & Products Websockets
Websockets ws

Wed, 15 Jul 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 15 Jul 2026 17:30:00 +0000

Type Values Removed Values Added
Description ws before 8.21.1 contains a memory exhaustion vulnerability in lib/receiver.js where the fragment guard only triggers when fragment count reaches maxFragments, allowing attackers to exhaust memory by sending incomplete fragmented WebSocket messages. Attackers can send a text frame with FIN=0 followed by continuation frames without completing the sequence, causing each fragment to be stored as a separate Buffer object with significant overhead, enabling denial of service through heap exhaustion.
Title ws < 8.21.1 Default maxFragments Allows Memory Exhaustion DoS
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: REJECTED

Assigner: VulnCheck

Published:

Updated: 2026-07-29T17:23:48.982Z

Reserved: 2026-07-13T22:40:54.412Z

Link: CVE-2026-62389

cve-icon Vulnrichment

Updated:

cve-icon NVD

Status : Rejected

Published: 2026-07-15T18:16:49.893

Modified: 2026-07-29T18:16:57.713

Link: CVE-2026-62389

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-31T03:15:04Z

Weaknesses