CVE-2026-101906 Axios: ReDoS (O(N²)) in shouldBypassProxy host normalization, reachable via untrusted redirect Location
Attackers can cause denial of service in Axios by triggering quadratic regex backtracking via crafted redirect hostnames when proxy bypass settings are configured.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-101906?
CVE-2026-101906 is a high-severity denial of service vulnerability in axios, published on 28 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Axios is a promise-based HTTP client for the browser and Node.js. From 1.15.0 until 1.20.0, Axios shouldBypassProxy applies a quadratic trailing-dot regular expression to redirect hostnames. HTTP_PROXY or HTTPS_PROXY is configured, NO_PROXY or no_proxy is non-empty, redirects are followed, and a crafted redirect Location contains many dots followed by a non-dot character. Hostname.replace(/.+$/, '') backtracks quadratically while processing the crafted redirect hostname. Synchronous regular-expression processing can block the Node.js event loop and cause denial of service. This issue is fixed in version 1.20.0.
Which versions are affected by CVE-2026-101906?
2 open source packages ship an affected version, including axios.
| Package | Affected | Fixed in |
|---|---|---|
axios npm | From 1.15.0 | 1.20.0 |
axios npm | From 1.15.0 | 1.20.0 |
How do I fix CVE-2026-101906?
Upgrade axios to 1.20.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-101906 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101906 exists.
Sources
Also known as CLEANSTART-2026-GY66727, CLEANSTART-2026-LO23632, CLEANSTART-2026-SE41878, DEBIAN-CVE-2026-101906, ECHO-6280-5ea2-cc61, GHSA-mghh-pgcx-3jjj and 13 more.