CVE-2026-48804

Name	CVE-2026-48804
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1144515

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python-engineio (PTS)	bookworm	4.3.4-2	vulnerable
	trixie	4.11.2-1	vulnerable
	forky, sid	4.13.0-2	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
python-engineio	source	(unstable)	(unfixed)			1144515

Notes

[trixie] - python-engineio <no-dsa> (Minor issue)
[bookworm] - python-engineio <postponed> (Minor issue)
https://github.com/miguelgrinberg/python-socketio/security/advisories/GHSA-5w7q-77mv-v69f
Fixed by: https://github.com/miguelgrinberg/python-socketio/commit/4bec3ef87bcfd6ab5b94cd3ac09d873283a6960e (v5.16.4)