axios: Improper Neutralization of CRLF Sequences in HTTP Headers
CVE-2026-42035 is a high-severity improper neutralization of CRLF sequences in HTTP headers vulnerability in axios, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected axios versions: >= 1.0.0, < 1.15.1; < 0.31.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.4% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of axios you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (github.com).
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of CRLF Sequences in HTTP Headers
The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers.
How developers prevent this class of flaw
- Construct HTTP headers very carefully, avoiding the use of non-validated input data.
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
More Improper Neutralization of CRLF Sequences in HTTP Headers vulnerabilities (CWE-113)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/axios/axios/security/advisories/GHSA-6chq-wfr3-2hj9Exploit, Mitigation
Other vulnerabilities in axios
- 8.3 High severity
- 7.0 High severity
- 8.2 High severity
- 7.6 High severity
- 8.2 High severity
- 8.2 High severity
Recent Improper Neutralization of CRLF Sequences in HTTP Headers vulnerabilities
- 7.2 High severity
- 8.8 High severity
- 8.7 High severity
- 7.3 High severity
- 8.9 High severity
- 8.8 High severity
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