{"id":"CVE-2026-44372","aliases":["GHSA-9phm-9p8f-hw5m"],"url":"https://o3.security/vulnerability/CVE-2026-44372","summary":"Nitro: Open Redirect via Protocol-Relative URL Bypass in Wildcard Route Rules","details":"A redirect route rule like:\n\n```ts\nrouteRules: {\n  \"/legacy/**\": { redirect: \"/**\" }\n}\n```\n\nis intended to rewrite paths within the same host. Before the patch, an attacker could turn the rewrite into a cross-host redirect by sliding an extra slash in after the rule prefix. Example exploit:\n\n```\nGET /legacy//evil.com\n```\n\nNitro stripped `/legacy` from the matched pathname and joined the remainder against the rule's target. The remainder was `//evil.com`, which the join preserved verbatim, so Nitro responded with `Location: //evil.com`. Browsers resolve `//evil.com` as a protocol-relative URL against the current scheme, sending the user to `https://evil.com`. \n\n### Are you affected?\n\nUsers may be affected if **all** of the following are true:\n\n1. Their project uses Nitro's `routeRules` with a `redirect` entry.\n2. The target uses a `/**` wildcard suffix to forward sub-paths (e.g. `redirect: \"/**\"`, `redirect: \"/new/**\"`, `proxy: { to: \"http://upstream/**\" }`).\n3. The `redirect` rule is _not_ handled natively at the CDN layer. The `vercel`, `netlify`, `cloudflare-pages`, and `edgeone` presets translate `routeRules.redirect` into platform config (`vercel.json`, `_redirects`, EdgeOne v3 config) and serve the redirect at the edge — those deployments bypass the Nitro runtime entirely and are not affected. Every other preset executes the redirect through the Nitro runtime and can be vulnerable.\n\n## Impact\n\nOpen redirect from any host serving Nitro with a wildcard `redirect` rule. The redirect target is fully attacker-controlled, the URL looks legitimate (it starts with the victim's domain), and the browser silently follows it.\n\n## Patched versions\n\nUpgrade to one of:\n\n- [2.13.4](https://github.com/nitrojs/nitro/releases/tag/v2.13.4) or later (or upgrade lockfile with latest ufo 1.6.4+)\n- [3.0.260429-beta](https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta) or later (https://github.com/nitrojs/nitro/pull/4236)\n\nThe fix has two parts:\n\n1. `ufo` is bumped to `^1.6.4` ([unjs/ufo@5cd9e67](https://github.com/unjs/ufo/commit/5cd9e676711af3f4e4b5398ddf6ca8d52c1c7e1f)), which collapses any run of leading slashes to a single `/` inside `withoutBase`. This covers the typical `\"/scope/**\"` rule.\n2. The Nitro runtime additionally collapses leading `//` before joining when the rule path itself is `/**` (in rare case which case `withoutBase` is never called and the raw pathname flows straight into `joinURL(\"\", …)`).","published":"2026-05-13T20:30:44.943Z","modified":"2026-08-12T03:51:39.608825591Z","cvss":null,"epss":{"score":0.00233,"percentile":0.14014,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"nitro","fixedVersion":"3.0.260429-beta"},{"ecosystem":"npm","name":"nitropack","fixedVersion":"2.13.4"}],"fix":{"url":"https://github.com/nitrojs/nitro/pull/4236","label":"nitrojs/nitro#4236"},"references":[{"type":"WEB","url":"https://github.com/nitrojs/nitro/releases/tag/v2.13.4"},{"type":"WEB","url":"https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44372.json"},{"type":"ADVISORY","url":"https://github.com/nitrojs/nitro/security/advisories/GHSA-9phm-9p8f-hw5m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44372"},{"type":"FIX","url":"https://github.com/nitrojs/nitro/pull/4236"},{"type":"WEB","url":"https://github.com/unjs/ufo/commit/5cd9e676711af3f4e4b5398ddf6ca8d52c1c7e1f"},{"type":"PACKAGE","url":"https://github.com/nitrojs/nitro"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:39.608825591Z"}}