CVE-2026-48804: python-socketio Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-5w7q-77mv-v69f
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CVSS 7.5
CWE-770
Published
Advisory Summary

CVE-2026-48804 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting python-socketio libraries in the PyPI ecosystem. The issue involves binary attachment accumulation can cause denial of service. Remediation is available by upgrading affected packages to version 5.16.2.

CVE-2026-48804 at a Glance

CVE Identifier CVE-2026-48804
GHSA Identifier GHSA-5w7q-77mv-v69f
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product python-socketio
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-48804

To remediate this vulnerability, upgrade all affected python-socketio dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

python-socketio fixed: 5.16.2 
pip install python-socketio>=5.16.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show python-socketio

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-48804, inspect your installed packages using pip:

pip show python-socketio

Analyze the terminal output to locate any version of python-socketio in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.16.2), your application is affected.

Note: The pip show python-socketio command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In python-socketio, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact The python-socketio server stores binary `EVENT` and `ACK` messages in memory while it waits to receive their binary attachments. Once all the attachments are received, these messages are then processed. An attacker can submit a binary message and intentionally omit sending one or more of its attachments to cause the message along with the partial list of received attachments to stay in memory for a long time. ### Patches Version 5.16.2 takes the following measures to address this issue: - Binary packets are only accepted from authenticated clients. - When a client disconnects, the server checks if there is a partial binary message being held for the client and deletes it.

CVE-2026-48804 Affected python-socketio Versions

1 component(s)
Fixed Versions:
5.16.2
Product / Package Ecosystem Affected Versions Fixed Version
python-socketio
pypi/python-socketio
PyPI
< 5.16.2
5.16.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/miguelgrinberg/python-socketio/security/advisories/GHSA-5w7q-77mv-v69f
python-socketio Source Repository REPOSITORY
https://github.com/miguelgrinberg/python-socketio

Frequently Asked Questions

What is CVE-2026-48804?
CVE-2026-48804 is a security vulnerability in python-socketio involving Binary attachment accumulation can cause denial of service under CWE-770: Allocation of Resources Without Limits or Throttling.
Which python-socketio versions are affected?
Affected versions include releases prior to 5.16.2 across affected packages: python-socketio.
What version fixes CVE-2026-48804?
Upgrading to 5.16.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is python-socketio affected?
Yes, python-socketio is affected in releases prior to 5.16.2. Upgrade your dependency to 5.16.2 or later.
What is the CVSS score of CVE-2026-48804?
CVE-2026-48804 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-48804?
CVE-2026-48804 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check PyPI dependencies for CVE-2026-48804?
Run the dependency tree command: 'pip show python-socketio'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
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  "schema_version" : "1.4.0",
  "id" : "GHSA-5w7q-77mv-v69f",
  "modified" : "2026-06-26T20:51:58Z",
  "published" : "2026-06-26T20:51:58Z",
  "aliases" : [ "CVE-2026-48804" ],
  "summary" : "python-socketio: Binary attachment accumulation can cause denial of service",
  "details" : "### Impact\nThe python-socketio server stores binary `EVENT` and `ACK` messages in memory while it waits to receive their binary attachments. Once all the attachments are received, these messages are then processed. An attacker can submit a binary message and intentionally omit sending one or more of its attachments to cause the message along with the partial list of received attachments to stay in memory for a long time.\n\n### Patches\nVersion 5.16.2 takes the following measures to address this issue:\n- Binary packets are only accepted from authenticated clients.\n- When a client disconnects, the server checks if there is a partial binary message being held for the client and deletes it.",
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  "references" : [ {
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  "database_specific" : {
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    "severity" : "HIGH",
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    "github_reviewed_at" : "2026-06-26T20:51:58Z",
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}