{"id":"CVE-2026-48804","aliases":["GHSA-5w7q-77mv-v69f","PYSEC-2026-3042"],"url":"https://o3.security/vulnerability/CVE-2026-48804","summary":"python-socketio: Binary attachment accumulation can cause denial of service","details":"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.","published":"2026-08-11T19:17:53.687Z","modified":"2026-09-12T03:30:42.737382570Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":{"score":0.00279,"percentile":0.20424,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"python-socketio","fixedVersion":"5.16.2"}],"fix":{"url":"https://github.com/miguelgrinberg/python-socketio/commit/4bec3ef87bcfd6ab5b94cd3ac09d873283a6960e","label":"miguelgrinberg/python-socketio@4bec3ef"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48804.json"},{"type":"ADVISORY","url":"https://github.com/miguelgrinberg/python-socketio/security/advisories/GHSA-5w7q-77mv-v69f"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48804"},{"type":"FIX","url":"https://github.com/miguelgrinberg/python-socketio/commit/4bec3ef87bcfd6ab5b94cd3ac09d873283a6960e"},{"type":"PACKAGE","url":"https://github.com/miguelgrinberg/python-socketio"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-12T03:30:42.737382570Z"}}