How severe is CVE-2026-59724?

CVE-2026-59724 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-59724 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59724?

CVE-2026-59724 affects Socket Engine.io. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59724?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-59724 published?

CVE-2026-59724 was published on 2026-07-08 and last updated on 2026-07-13.

CVE-2026-59724

CVE-2026-59724 is a high-severity vulnerability in Socket Engine.io with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (27th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Socket Engine.io
Published: 2026-07-08
Last modified: 2026-07-13

Description

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.

Frequently asked questions

What is CVE-2026-59724?: 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.
How severe is CVE-2026-59724?: CVE-2026-59724 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-59724 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59724?: CVE-2026-59724 affects Socket Engine.io. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59724?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-59724 published?: CVE-2026-59724 was published on 2026-07-08 and last updated on 2026-07-13.

References

Affected products (1)

cpe:2.3:a:socket:engine.io:*:*:*:*:*:node.js:*:*

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