CVE-2025-7339 is a low-severity (CVSS 3.4) CWE-241 vulnerability in on-headers. A fix is available for on-headers — see the affected versions and patch details below.
on-headers vulnerable to http response header manipulation
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-7339.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2025-7339 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
on-headersnpmDescription
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | on-headers | all versions | 1.1.0npm install on-headers@1.1.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for on-headers, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update on-headers to 1.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-7339 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-7339 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-7339. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Openshift Data Foundation 4.20 | odf4/cephcsi-rhel9:v4.20-1761848902 | RHSA-2025:21704 |
Frequently Asked Questions
Is CVE-2025-7339 in your dependencies?
O3 Security finds CVE-2025-7339 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.