CVE-2026-44373 Nitro: Proxy scope bypass via percent-encoded path traversal in `routeRules`
Attackers can bypass proxy route rules using percent-encoded path traversal, causing requests to be forwarded outside the configured scope.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44373?
CVE-2026-44373 is a medium-severity path traversal vulnerability in nitrojs nitro, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Nitro is a next generation server toolkit. Prior to 3.0.260429-beta, an attacker could bypass a proxy route rule by sending percent-encoded path traversal (..%2f) in the URL, causing Nitro to forward a request that the upstream resolved outside the configured scope. This vulnerability is fixed in 3.0.260429-beta.
Weakness: CWE-22
Which versions are affected by CVE-2026-44373?
4 open source packages ship an affected version, including nitro and nitropack. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
nitro npm | All versions | 3.0.260429-beta |
nitro npm | All versions | 3.0.260429-beta |
nitropack npm | All versions | 2.13.4 |
nitropack npm | All versions | 2.13.4 |
Products include Nitro Nitro.
How do I fix CVE-2026-44373?
Upgrade nitro to 3.0.260429-beta or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-44373 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44373 exists.
Other vulnerabilities in nitrojs nitro
Sources
Also known as GHSA-5w89-w975-hf9q.