CVE-2025-7339

low-risk
Published 2025-07-17

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.

Do I need to act?

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0.01% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
3
CVSS 3.4/10 Low
LOCAL / LOW complexity
18
/ 100
low-risk
Severity 13/34 · Low
Exploitability 0/34 · Minimal
Exposure 5/34 · Minimal