{"id":"CVE-2026-44217","aliases":["GHSA-84hm-wfh8-c5pg"],"url":"https://o3.security/vulnerability/CVE-2026-44217","summary":"sse-channel: SSE Injection via unsanitized event fields","details":"### Impact\n\nImplementations that allows user-provided values to be passed to `event`, `retry` or `id` fields would be susceptible to event spoofing, where an attacker could inject arbitrary messages into the stream.\n\n- **Event Spoofing:** Attacker can inject arbitrary SSE events into the stream\n- **Client-side Manipulation:** Injected events can trigger unintended behavior in frontend JavaScript EventSource listeners\n- **Data Integrity:** Consumers of the SSE stream cannot distinguish injected events from legitimate ones\n\n### Patches\nPatch available in v4.0.1.\n\n### Workarounds\nDo not allow user data to control `event`, `retry` or `id` fields, and if you must - sanitize the input before passing it to `sse-channel`, stripping any newlines. \n\n### Resources\n\nhttps://github.com/rexxars/sse-channel/issues/42","published":"2026-05-12T19:51:06.910Z","modified":"2026-08-12T03:51:12.538577827Z","cvss":null,"epss":{"score":0.00479,"percentile":0.39112,"asOf":"2026-08-13"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"sse-channel","fixedVersion":"4.0.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44217.json"},{"type":"ADVISORY","url":"https://github.com/rexxars/sse-channel/security/advisories/GHSA-84hm-wfh8-c5pg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44217"},{"type":"REPORT","url":"https://github.com/rexxars/sse-channel/issues/42"},{"type":"PACKAGE","url":"https://github.com/rexxars/sse-channel"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:12.538577827Z"}}