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Fencer Vulns
high 7.5

CVE-2026-59724 json

Socket.IO: Engine.IO WebTransport SID DoS

published 2026-07-08 4 mo ago modified 2026-10-25 14 d ago also GHSA-gr94-w7qr-f4j3 , EUVD-2026-42312

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

Socket.IO enables bidirectional and low-latency communication for every platform. From 6.5.0 before 6.6.7, Engine.IO servers with WebTransport enabled can resolve a crafted session ID such as __proto__ through an inherited property of the clients object during WebTransport upgrade handling, causing a TypeError and denial of service. This issue is fixed in version 6.6.7.

Patch / fix

  • npm engine.io 6.6.7
  • socket engine.io 6.6.7
  • dotnet8.0 hummingbird 1 8.0.128-1.hum1
  • dotnet-sdk-8.0 hummingbird 1 8.0.128-1.hum1
  • dotnet-sdk-dbg-8.0 hummingbird 1 8.0.128-1.hum1
  • dotnet-templates-8.0 hummingbird 1 8.0.128-1.hum1
  • dotnet-sdk-8.0-source-built-artifacts hummingbird 1 8.0.128-1.hum1

red hat advisories RHSA-2026:26994

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-59724 updated cvss 7.5

engine.io: Engine.IO: Denial of Service via crafted WebTransport session ID

  • Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/disk-image-cuda-rhel9
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat Hardened Images dotnet8.0 8.0.128-1.hum1, dotnet-sdk-8.0 8.0.128-1.hum1, dotnet-sdk-dbg-8.0 8.0.128-1.hum1, dotnet-templates-8.0 8.0.128-1.hum1, dotnet-sdk-8.0-source-built-artifacts 8.0.128-1.hum1
    fixed: vendor fix RHSA-2026:26994
  • Red Hat Hardened Images dotnet-hostfxr-8.0 8.0.28-1.hum1, dotnet-runtime-8.0 8.0.28-1.hum1, aspnetcore-runtime-8.0 8.0.28-1.hum1, dotnet-runtime-dbg-8.0 8.0.28-1.hum1, dotnet-apphost-pack-8.0 8.0.28-1.hum1, dotnet-targeting-pack-8.0 8.0.28-1.hum1, +2 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm engine.io
>=6.5.0, <6.6.7
6.6.7

Affected products

  • socketio socket.io

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.