CVE-2025-7339
CVE-2025-7339 is a low-severity vulnerability with a CVSS 3.x base score of 3.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-241.
Key facts
- Severity: Low (CVSS 3.x base score 3.4)
- EPSS exploit prediction: 0% (7th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-21784
- Weakness: CWE-241
- Published:
- Last modified:
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.
Frequently asked questions
- What is 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.
- How severe is CVE-2025-7339?
- CVE-2025-7339 has a CVSS 3.x base score of 3.4, rated low severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
- Is CVE-2025-7339 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2025-7339?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2025-7339 have an EU (EUVD) identifier?
- Yes. CVE-2025-7339 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-21784.
- When was CVE-2025-7339 published?
- CVE-2025-7339 was published on 2025-07-17 and last updated on 2026-06-17.
References
- https://cna.openjsf.org/security-advisories.html
- https://github.com/expressjs/morgan/issues/315
- https://github.com/jshttp/on-headers/commit/c6e384908c9c6127d18831d16ab0bd96e1231867
- https://github.com/jshttp/on-headers/issues/15
- https://github.com/jshttp/on-headers/security/advisories/GHSA-76c9-3jph-rj3q
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