CVE-2026-44217 sse-channel: SSE Injection via unsanitized event fields
Attackers can inject arbitrary messages into Server-Sent Events streams by exploiting unsanitized event fields in the sse-channel library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44217?
CVE-2026-44217 is a medium-severity vulnerability in rexxars sse-channel, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
sse-channel is an SSE-implementation which can be used to any node.js http request/response stream. Prior to 4.0.1, implementations that allow user-provided values to be passed to event, retry or id fields are susceptible to event spoofing, where an attacker could inject arbitrary messages into the stream. This vulnerability is fixed in 4.0.1.
Weakness: CWE-93
Which versions are affected by CVE-2026-44217?
2 open source packages ship an affected version, including sse-channel.
| Package | Affected | Fixed in |
|---|---|---|
sse-channel npm | All versions | 4.0.1 |
sse-channel npm | All versions | 4.0.1 |
How do I fix CVE-2026-44217?
Upgrade sse-channel to 4.0.1 or later.
Is CVE-2026-44217 being exploited?
There is no known exploitation of CVE-2026-44217 in the wild and no public exploit code.
Sources
Also known as GHSA-84hm-wfh8-c5pg.