CVE-2026-29085CWE-74

Hono: SSE Control Field Injection via CR/LF in writeSSE()

Medium · published March 4, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
22.6
In the wild
Unconfirmed
What it is

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to version 4.12.4, when using streamSSE() in Streaming Helper, the event, id, and retry fields were not validated for carriage return (\r) or newline (\n) characters. Because the SSE protocol uses line breaks as field delimiters, this could allow injection of additional SSE fields within the same event frame if untrusted input was passed into these fields. This issue has been patched in version 4.12.4.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00310 · 22.6th percentile
Weakness
CWE-74 · Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Published
2026-03-04T22:09Z
EPSS history
Timeline
  • 04 MAR 22:09Z
    Hono: SSE Control Field Injection via CR/LF in writeSSE()
    cvelistv5