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Fencer Vulns
high 7.5

CVE-2026-48804 json

python-socketio: Binary attachment accumulation can cause denial of service

published 2026-06-26 4 mo ago modified 2026-09-10 59 d ago also GHSA-5w7q-77mv-v69f , PYSEC-2026-3042 , EUVD-2026-56894

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

python-socketio is a Python implementation of the Socket.IO realtime client and server. 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. Prior to version 5.16.4, 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. Version 5.16.4 takes the following measures to address this issue: Binary packets are only accepted from authenticated clients and, when a client disconnects, the server checks if there is a partial binary message being held for the client and deletes it.

Patch / fix

  • pypi python-socketio 5.16.2
  • python-socketio Debian 14 5.17.0-1

debian advisories DEBIAN-CVE-2026-48804

  • python-python-socketio SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Python 3 15 SP7 5.7.2-150600.3.6.1

suse advisories SUSE-SU-2026:3086-1

  • python-python-socketio openSUSE Tumbleweed 5.16.3-1.1

opensuse advisories openSUSE-SU-2026:11171-1

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-2026-48804 updated cvss 7.5

socketio: python-socketio: Denial of Service via binary attachment accumulation

  • Red Hat All currently supported Red Hat products
    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
2 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% 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
OSV 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
pypi python-socketio
<5.16.2
5.16.2

Affected products

  • miguelgrinberg python-socketio

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

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.