Summaryinfo

A vulnerability was found in socketio socket.io up to 3.3.4/3.4.3/4.2.5. It has been classified as critical. This impacts an unknown function. Performing a manipulation results in buffer overflow. This vulnerability is cataloged as CVE-2026-33151. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, was found in socketio socket.io up to 3.3.4/3.4.3/4.2.5. This affects an unknown code block. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. This is going to have an impact on availability. The summary by CVE is:

Socket.IO is an open source, real-time, bidirectional, event-based, communication framework. Prior to versions 3.3.5, 3.4.4, and 4.2.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This issue has been patched in versions 3.3.5, 3.4.4, and 4.2.6.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-33151 since 03/17/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 303255 (Linux Distros Unpatched Vulnerability : CVE-2026-33151), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 3.3.5, 3.4.4 or 4.2.6 eliminates this vulnerability. Applying the patch 719f9ebab0772ffb882bd614b387e585c1aa75d4 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (303255). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• socketio

Name

• socket.io

Version

• 3.3.0
• 3.3.1
• 3.3.2
• 3.3.3
• 3.3.4
• 3.4.0
• 3.4.1
• 3.4.2
• 3.4.3
• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3
• 4.2.4
• 4.2.5

License

• open-source

Website

• Product: https://github.com/socketio/socket.io/

CPE 2.3info

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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