Vulnerability · Published May 12, 2026 · Assigned by GitHub_M

CVE-2026-44217sse-channel: SSE Injection via unsanitized event fields

Medium 6.6

In plain English

A medium-severity security flaw in sse-channel from rexxars. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.6Medium

Exploit odds (30 days)0.5%top 58.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	sse-channel	4.0.1	GHSA-84hm-wfh8-c5pg

Affected products (as reported)

Vendor	Product	Versions
rexxars	sse-channel	< 4.0.1

Weakness: CWE-93 · Vector: 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

References

https://github.com/rexxars/sse-channel/security/advisories/GHSA-84hm-wfh8-c5pg x_refsource_CONFIRM
https://github.com/rexxars/sse-channel/issues/42 x_refsource_MISC