# CVE-2026-101906: Axios ReDoS in shouldBypassProxy regular expression

Source: https://junglewise.ai/threats/cve-2026-101906-axios-is-a-promise-based-http-client-for-the-browser-and-node-js  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-28. Updated: 2026-09-28  
License: CC BY 4.0 with a link back

CVE-2026-101906 · Severity: high · CVSS 4 · Published 2026-09-28

Axios, a popular HTTP client library for Node.js and browsers, contains a regular expression that processes redirect hostnames inefficiently. When configured to use a proxy with NO_PROXY filtering and following HTTP redirects, an attacker can craft a redirect with a specially formatted hostname containing many dots that causes the regex engine to backtrack excessively, blocking the Node.js event loop and causing denial of service.

Technologies: [Axios](https://junglewise.ai/threats/technologies/axios), [axios (npm)](https://junglewise.ai/threats/technologies/npm-axios). Vendors: [Axios](https://junglewise.ai/threats/vendors/axios), [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-101906 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101906 being exploited in the wild.

**How severe is CVE-2026-101906?** High severity, with a CVSS score of 4, published 28 September 2026.

**Which products and versions are affected?** Axios 1.15.0 through 1.19.x; axios (npm) >= 1.15.0, < 1.20.0, SEMVER:introduced=1.15.0,fixed=1.20.0.

**Is there a fix for CVE-2026-101906?** Yes. axios (npm): upgrade to 1.20.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-101906 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-101906?** Check whether you run Axios or axios (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- axios (npm): upgrade to 1.20.0 or later

  ```sh
  npm install axios@1.20.0
  ```


## Technical details

The vulnerability is a ReDoS (Regular Expression Denial of Service) in the shouldBypassProxy function that applies a quadratic-complexity trailing-dot regex pattern to redirect hostnames. The attack requires HTTP_PROXY/HTTPS_PROXY and NO_PROXY environment variables to be configured, redirect following enabled, and a crafted redirect Location header with many dots followed by a non-dot character. Synchronous regex processing blocks the event loop causing denial of service; the issue is fixed in version 1.20.0.

## Affected products

- axios axios 1.15.0 through 1.19.x

## Identifiers

- CVE-2026-101906
- GHSA-mghh-pgcx-3jjj

## Timeline

- 2026-09-28: disclosed

## References

- [https://github.com/axios/axios/commit/d19040bda7a8be2f82c3c6e1a5bc03917daee39a](https://github.com/axios/axios/commit/d19040bda7a8be2f82c3c6e1a5bc03917daee39a)
- [https://github.com/axios/axios/pull/11141](https://github.com/axios/axios/pull/11141)

## Related threats

- [Axios NO_PROXY CIDR notation bypass in Node.js adapter](https://junglewise.ai/threats/cve-2026-101899-axios-cidr-form-no-proxy-entries-are-ignored-causing-proxy)
- [Axios prototype pollution in ToFormData](https://junglewise.ai/threats/cve-2026-101909-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)
- [Axios fetch adapter header injection via prototype pollution](https://junglewise.ai/threats/cve-2026-101908-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)
- [Axios fetch adapter maxRedirects bypass](https://junglewise.ai/threats/cve-2026-101907-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)
- [Axios HTTP adapter prototype pollution leading to man-in-the-middle](https://junglewise.ai/threats/cve-2026-101905-axios-is-a-promise-based-http-client-for-the-browser-and-node-js)