Vulnerability in Jshttp On-Headers

CVE-2025-7339

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 3.4 (Low). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (7.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-7339: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-7339?
CVE-2025-7339 is a low-severity vulnerability in Jshttp On-Headers, classified under CWE-241. CVSS score: 3.4/10. Published 2025-07-17.
How severe is CVE-2025-7339?
Low severity. CVSS v3 base score is 3.4 out of 10.
Is CVE-2025-7339 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.