CVE-2026-101899 Axios: CIDR-form NO_PROXY entries are ignored, causing proxy exclusion bypass for internal IP ranges
Axios ignores CIDR-form NO_PROXY entries, causing internal requests to bypass intended exclusions and traverse configured proxies, exposing data to interception.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-101899?
CVE-2026-101899 is a medium-severity vulnerability in axios, published on 13 Oct 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 treats the NO_PROXY CIDR form as a textual hostname suffix instead of evaluating the network range. A request targets an address covered by a CIDR entry in NO_PROXY while a proxy is configured. The CIDR bypass rule is not matched, so the request is sent through the configured proxy. For plaintext HTTP, the proxy can observe and modify URLs, headers, and bodies; for HTTPS, it can observe connection metadata and CONNECT requests. This issue is fixed in version 1.20.0.
Weakness: CWE-693
Which versions are affected by CVE-2026-101899?
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-2026-101899?
Upgrade axios to 1.20.0 or later.
Is CVE-2026-101899 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-101899 exists.
Sources
Also known as CLEANSTART-2026-FC45371, CLEANSTART-2026-HE03730, CLEANSTART-2026-SK85007, DEBIAN-CVE-2026-101899, ECHO-322b-b4b4-8549, GHSA-44g4-m2mj-wpvx and 12 more.