CVE-2026-42044
MEDIUMCVE-2026-42044 is a medium-severity (CVSS 6.5) vulnerability in axios. O3 Security confirms whether CVE-2026-42044 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Axios: Invisible JSON Response Tampering via Prototype Pollution Gadget in `parseReviver`
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
axiosnpmDescription
Axios is a promise based HTTP client for the browser and Node.js. From 1.0.0 to before 1.15.2, he Axios library is vulnerable to a Prototype Pollution "Gadget" attack that allows any Object.prototype pollution in the application's dependency tree to be escalated into surgical, invisible modification of all JSON API responses — including privilege escalation, balance manipulation, and authorization bypass. The default transformResponse function at lib/defaults/index.js:124 calls JSON.parse(data, this.parseReviver), where this is the merged config object. Because parseReviver is not present in Axios defaults, not validated by assertOptions, and not subject to any constraints, a polluted Object.prototype.parseReviver function is called for every key-value pair in every JSON response, allowing the attacker to selectively modify individual values while leaving the rest of the response intact. This vulnerability is fixed in 1.15.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | axios | ≥ 1.0.0&&< 1.15.2 | 1.15.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for axios. 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.
Fix
Update axios to 1.15.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42044 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 pinpoints whether CVE-2026-42044 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 CVE-2026-42044. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-42044 in your dependencies?
O3 detects CVE-2026-42044 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.