Prototype Pollution in Axios
CVE-2026-42035
Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, a prototype pollution gadget exists in the Axios HTTP adapter (lib/adapters/http.js) that allows an attacker to inject arbitrary HTTP headers into outgoing requests. The vulnerability exploits duck-type checking of the data payload, where if Object.prototype is polluted with getHeaders, append, pipe, on, once, and Symbol.toStringTag, Axios misidentifies any plain object payload as a FormData instance and calls the attacker-controlled getHeaders() function, merging the returned headers into the outgoing request. The vulnerable code resides exclusively in lib/adapters/http.js. The prototype pollution source does not need to originate from Axios itself — any prototype pollution primitive in any dependency in the application's dependency tree is sufficient to trigger this gadget. This vulnerability is fixed in 1.15.1 and 0.31.1.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (29.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 29.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: -0.000
Affected products
- Axios — versions >= 1.0.0, < 1.15.1, < 0.31.1
Weakness classification (CWE)
References
- github.com/axios/axios/security/advisories/GHSA-6chq-wfr3-2hj9 (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-42035?
- CVE-2026-42035 is a high-severity vulnerability in Axios, classified under HTTP Response Splitting. CVSS score: 7.4/10. Published 2026-04-24.
- How severe is CVE-2026-42035?
- High severity. CVSS v3 base score is 7.4 out of 10.