CVE-2026-62389Public exploitNetwork attack vector

Process crash via retained fragmented-message buffers

Published Jul 15, 2026 · Updated Jul 15, 2026

Resource exhaustion in WebSockets ws before 8.21.1 allows remote attackers to crash a Node.js process with fragmented messages. lib/receiver.js retains each incomplete fragment as a separate Buffer while the fragment-count guard permits a sequence just below maxFragments, so wrapper overhead exhausts the heap. The gate is an unauthenticated network peer that can keep fragmented WebSocket messages incomplete; the CNA later rejected this identifier as a duplicate of CVE-2026-48779.

CVSS severity7.5
High
EPSS probabilityUnavailable
No score available in this record
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in WebSockets ws before 8.21.1 allows remote attackers to crash a Node.js process with fragmented messages. lib/receiver.js retains each incomplete fragment as a separate Buffer while the fragment-count guard permits a sequence just below maxFragments, so wrapper overhead exhausts the heap. The gate is an unauthenticated network peer that can keep fragmented WebSocket messages incomplete; the CNA later rejected this identifier as a duplicate of CVE-2026-48779.

The record

CVE
CVE-2026-62389
Published
Jul 15, 2026
Updated
Jul 15, 2026
Vendor
WebSockets
Product
ws
Classifications
CWE-770, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <8.21.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WebSockets · wsversion=0 <8.21.1

Published CVSS scores

8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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