Description
on-headers is a node.js middleware for listening to when a response writes headers. A bug in on-headers versions `<1.1.0` may result in response headers being inadvertently modified when an array is passed to `response.writeHead()`. Users should upgrade to version 1.1.0 to receive a patch. Uses are strongly encouraged to upgrade to `1.1.0`, but this issue can be worked around by passing an object to `response.writeHead()` rather than an array.
References (5)
Core 5
Core References
Various Sources
https://cna.openjsf.org/security-advisories.html
Issue Tracking
https://github.com/expressjs/morgan/issues/315
Issue Tracking
https://github.com/jshttp/on-headers/issues/15
Scores
CVSS v3
3.4
EPSS
0.0001
EPSS Percentile
1.3%
Attack Vector
LOCAL
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-241
Status
published
Products (2)
jshttp/on-headers
< 1.1.0
npm/on-headers
0 - 1.1.0npm
Published
Jul 17, 2025
Tracked Since
Feb 18, 2026