Bug 2514329 (CVE-2026-48804)

Summary: CVE-2026-48804 socketio: python-socketio: Denial of Service via binary attachment accumulation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in python-socketio, a Python implementation of the Socket.IO realtime client and server. The server stores binary messages in memory while awaiting their attachments. A remote attacker can exploit this by sending a binary message and deliberately withholding some attachments. This causes the incomplete messages to persist in memory, leading to excessive memory consumption and ultimately a Denial of Service (DoS) for the server.
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Bug Depends On: 2516177, 2516178    
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Description OSIDB Bzimport 2026-08-11 19:32:08 UTC 
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.