sse-channel: SSE Injection via unsanitized event fields

### Impact Implementations 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. - **Event Spoofing:** Attacker can inject arbitrary SSE events into the stream - **Client-side Manipulation:** Injected events can trigger unintended behavior in frontend JavaScript EventSource listeners - **Data Integrity:** Consumers of the SSE stream cannot distinguish injected events from legitimate ones ### Patches Patch available in v4.0.1. ### Workarounds Do 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. ### Resources https://github.com/rexxars/sse-channel/issues/42

Source published

5 May 2026 22:17:02 UTC

Source modified

13 May 2026 16:46:23 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U

Publisher rating · MODERATE