{"id":"CVE-2026-33151","aliases":["GHSA-677m-j7p3-52f9"],"url":"https://o3.security/vulnerability/CVE-2026-33151","summary":"socket.io allows an unbounded number of binary attachments","details":"### Impact\n\nA specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory.\n\n### Patches\n\n| Version range    | Used by                                    | Fixed version |\n|------------------|--------------------------------------------|---------------|\n| `>=4.0.0 <4.2.6` | `socket.io@4.x` and `socket.io-client@4.x` | `4.2.6`       |\n| `>=3.4.0 <3.4.4` | `socket.io@2.x`                            | `3.4.4`       |\n| `<3.3.5`         | `socket.io-client@2.x`                     | `3.3.5`       |\n\n### Workarounds\n\nThere is no known workaround except upgrading to a safe version.\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n\n- Open a discussion [here](https://github.com/socketio/socket.io/discussions)","published":"2026-03-20T20:13:31.424Z","modified":"2026-10-28T02:31:01.666642515Z","cvss":null,"epss":{"score":0.00514,"percentile":0.41413,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"socket.io-parser","fixedVersion":"3.3.5"},{"ecosystem":"npm","name":"socket.io-parser","fixedVersion":"3.4.4"},{"ecosystem":"npm","name":"socket.io-parser","fixedVersion":"4.2.6"}],"fix":{"url":"https://github.com/socketio/socket.io/commit/719f9ebab0772ffb882bd614b387e585c1aa75d4","label":"socketio/socket.io@719f9eb"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33151.json"},{"type":"ADVISORY","url":"https://github.com/socketio/socket.io/security/advisories/GHSA-677m-j7p3-52f9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33151"},{"type":"FIX","url":"https://github.com/socketio/socket.io/commit/719f9ebab0772ffb882bd614b387e585c1aa75d4"},{"type":"FIX","url":"https://github.com/socketio/socket.io/commit/9d39f1f080510f036782f2177fac701cc041faaf"},{"type":"FIX","url":"https://github.com/socketio/socket.io/commit/b25738c416c4e32fbff62ee182afa8f6d0dacf78"},{"type":"PACKAGE","url":"https://github.com/socketio/socket.io"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:01.666642515Z"}}