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📦 npm

GHSA-76c9-3jph-rj3q

LOW

GHSA-76c9-3jph-rj3q is a low-severity (CVSS 3.4) CWE-241 vulnerability in on-headers. O3 Security confirms whether GHSA-76c9-3jph-rj3q is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

on-headers is vulnerable to http response header manipulation

Also known asCVE-2025-7339
Published
Jul 17, 2025
Updated
Feb 4, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

Blast Radius

1 pkg affected
📦on-headers

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Impact

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()

Patches

Users should upgrade to 1.1.0

Workarounds

Uses are 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

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmon-headersall versions1.1.0

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for on-headers. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update on-headers to 1.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-76c9-3jph-rj3q is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-76c9-3jph-rj3q is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-76c9-3jph-rj3q. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact 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()` ### Patches Users should upgrade to `1.1.0` ### Workarounds Uses are 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.
O3 Security · Impact-Aware SCA

Is GHSA-76c9-3jph-rj3q in your dependencies?

O3 detects GHSA-76c9-3jph-rj3q across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.