Vulnerability-Lookup

CVE-2026-44373 (GCVE-0-2026-44373)

Vulnerability from cvelistv5 – Published: 2026-05-13 20:26 – Updated: 2026-05-14 13:16

Title

Nitro: Proxy scope bypass via percent-encoded path traversal in `routeRules`

Summary

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.

Severity

5.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-14 13:12 UTC

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7761 records in the last 180 days details

References

5 references

URL	Tags
https://github.com/nitrojs/nitro/security/advisor…	x_refsource_CONFIRM
https://github.com/nitrojs/nitro/pull/4222	x_refsource_MISC
https://github.com/nitrojs/nitro/pull/4223	x_refsource_MISC
https://github.com/nitrojs/nitro/releases/tag/v2.13.4	x_refsource_MISC
https://github.com/nitrojs/nitro/releases/tag/v3.…	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version	CPE status
nitrojs	nitro	Affected: < 3.0.260429-beta	guessed
nitrojs	nitropack	Affected: < 2.13.4	guessed

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-44373",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-14T13:12:25.544148Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-14T13:16:50.542Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "nitro",
          "vendor": "nitrojs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.0.260429-beta"
            }
          ]
        },
        {
          "product": "nitropack",
          "vendor": "nitrojs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.13.4"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-13T20:26:28.255Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q"
        },
        {
          "name": "https://github.com/nitrojs/nitro/pull/4222",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/nitrojs/nitro/pull/4222"
        },
        {
          "name": "https://github.com/nitrojs/nitro/pull/4223",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/nitrojs/nitro/pull/4223"
        },
        {
          "name": "https://github.com/nitrojs/nitro/releases/tag/v2.13.4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/nitrojs/nitro/releases/tag/v2.13.4"
        },
        {
          "name": "https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta"
        }
      ],
      "source": {
        "advisory": "GHSA-5w89-w975-hf9q",
        "discovery": "UNKNOWN"
      },
      "title": "Nitro: Proxy scope bypass via percent-encoded path traversal in `routeRules`"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-44373",
    "datePublished": "2026-05-13T20:26:28.255Z",
    "dateReserved": "2026-05-05T20:15:20.631Z",
    "dateUpdated": "2026-05-14T13:16:50.542Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-44373",
      "date": "2026-10-16",
      "epss": "0.00574",
      "percentile": "0.46195"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "nitro",
                "vendor": "nitrojs",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 3.0.260429-beta"
                  }
                ]
              },
              {
                "product": "nitropack",
                "vendor": "nitrojs",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 2.13.4"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:nitro:nitro:*:*:*:*:*:node.js:*:*",
                    "matchCriteriaId": "E81D7EC1-9EE7-4CC1-8DF1-22517FF21CBE",
                    "versionEndExcluding": "2.13.4",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:a:nitro:nitro:*:*:*:*:*:node.js:*:*",
                    "matchCriteriaId": "A93AAA84-4EDA-4708-8BEC-01E4D566A7B1",
                    "versionEndExcluding": "3.0.260429",
                    "versionStartExcluding": "2.13.4",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "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."
          }
        ],
        "id": "CVE-2026-44373",
        "lastModified": "2026-06-17T10:50:34.033",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 5.3,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "LOW",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 3.9,
              "impactScore": 1.4,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-44373",
                "options": [
                  {
                    "exploitation": "poc"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-14T13:12:25.544148Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-05-13T21:16:48.033",
        "references": [
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Issue Tracking",
              "Patch"
            ],
            "url": "https://github.com/nitrojs/nitro/pull/4222"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Issue Tracking",
              "Patch"
            ],
            "url": "https://github.com/nitrojs/nitro/pull/4223"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Release Notes"
            ],
            "url": "https://github.com/nitrojs/nitro/releases/tag/v2.13.4"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Release Notes"
            ],
            "url": "https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Third Party Advisory"
            ],
            "url": "https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Analyzed",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-22"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "current_release_date": "2026-06-05T19:25:29+00:00",
      "cve": "CVE-2026-44373",
      "id": "CVE-2026-44373",
      "initial_release_date": "2026-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "Nitro: Proxy scope bypass via percent-encoded path traversal in `routeRules`",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44373.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-44373",
                    "options": [
                      {
                        "Exploitation": "poc"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-05-14T13:12:25.544148Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-05-14T13:12:29.892Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "product": "nitro",
              "vendor": "nitrojs",
              "versions": [
                {
                  "status": "affected",
                  "version": "\u003c 3.0.260429-beta"
                }
              ]
            },
            {
              "product": "nitropack",
              "vendor": "nitrojs",
              "versions": [
                {
                  "status": "affected",
                  "version": "\u003c 2.13.4"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "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."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 5.3,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "LOW",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
                "version": "3.1"
              }
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-22",
                  "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-05-13T20:26:28.255Z",
            "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
            "shortName": "GitHub_M"
          },
          "references": [
            {
              "name": "https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q",
              "tags": [
                "x_refsource_CONFIRM"
              ],
              "url": "https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q"
            },
            {
              "name": "https://github.com/nitrojs/nitro/pull/4222",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/nitrojs/nitro/pull/4222"
            },
            {
              "name": "https://github.com/nitrojs/nitro/pull/4223",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/nitrojs/nitro/pull/4223"
            },
            {
              "name": "https://github.com/nitrojs/nitro/releases/tag/v2.13.4",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/nitrojs/nitro/releases/tag/v2.13.4"
            },
            {
              "name": "https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta"
            }
          ],
          "source": {
            "advisory": "GHSA-5w89-w975-hf9q",
            "discovery": "UNKNOWN"
          },
          "title": "Nitro: Proxy scope bypass via percent-encoded path traversal in `routeRules`"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "assignerShortName": "GitHub_M",
        "cveId": "CVE-2026-44373",
        "datePublished": "2026-05-13T20:26:28.255Z",
        "dateReserved": "2026-05-05T20:15:20.631Z",
        "dateUpdated": "2026-05-14T13:16:50.542Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

FKIE_CVE-2026-44373

Vulnerability from fkie_nvd - Published: 2026-05-13 21:16 - Updated: 2026-06-17 10:50

Severity

5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/nitrojs/nitro/pull/4222	Issue Tracking, Patch
security-advisories@github.com	https://github.com/nitrojs/nitro/pull/4223	Issue Tracking, Patch
security-advisories@github.com	https://github.com/nitrojs/nitro/releases/tag/v2.13.4	Release Notes
security-advisories@github.com	https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta	Release Notes
security-advisories@github.com	https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q	Third Party Advisory

Impacted products

	Vendor	Product	Version
	nitro	nitro	*
	nitro	nitro	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "nitro",
          "vendor": "nitrojs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.0.260429-beta"
            }
          ]
        },
        {
          "product": "nitropack",
          "vendor": "nitrojs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.13.4"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:nitro:nitro:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "E81D7EC1-9EE7-4CC1-8DF1-22517FF21CBE",
              "versionEndExcluding": "2.13.4",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:nitro:nitro:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "A93AAA84-4EDA-4708-8BEC-01E4D566A7B1",
              "versionEndExcluding": "3.0.260429",
              "versionStartExcluding": "2.13.4",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "id": "CVE-2026-44373",
  "lastModified": "2026-06-17T10:50:34.033",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-44373",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-14T13:12:25.544148Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-13T21:16:48.033",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Issue Tracking",
        "Patch"
      ],
      "url": "https://github.com/nitrojs/nitro/pull/4222"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Issue Tracking",
        "Patch"
      ],
      "url": "https://github.com/nitrojs/nitro/pull/4223"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/nitrojs/nitro/releases/tag/v2.13.4"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-5W89-W975-HF9Q

Vulnerability from github – Published: 2026-05-06 23:01 – Updated: 2026-05-14 20:42

Summary

Nitro has a proxy scope bypass via percent-encoded path traversal in `routeRules`

Details

A proxy route rule like:

routeRules: {
  "/api/orders/**": { proxy: { to: "http://upstream/orders/**" } }
}

is intended to limit the proxy to URLs under /api/orders/. Before the patch, an attacker could bypass that scope by sending percent-encoded path traversal (..%2f) in the URL, causing Nitro to forward a request that the upstream resolved outside the configured scope. Example exploit:

GET /api/orders/..%2fadmin%2fconfig.json

Nitro sees ..%2f as opaque characters at match time, the /api/orders/** rule matched, and the raw path was forwarded to the upstream as /orders/..%2fadmin/config.json. An upstream that decodes %2F to / then resolved .. and can serve /admin/config.json outside the intended scope.

Are you affected?

Users may be affected if ALL of the following are true:

Their project uses Nitro's routeRules with a proxy entry ({ proxy: { to: "..." } }).
The proxy to value uses a /** wildcard suffix to forward sub-paths.
The upstream behind the proxy decodes %2F as / before routing or filesystem lookup.
Proxy route rules are not handled natively at CDN (nitro v3 and vercel)

Whether the bypass actually leaks data depends on the upstream. Modern JS frameworks keep %2F opaque per RFC 3986 and are safe by construction.

Safe examples: H3 v2, Express v5, Hono v4 — modern JS frameworks keep %2F opaque per RFC 3986.
Vulnerable examples: naive imlementations that decodes the URL, static file servers, CGI dispatchers, Python os.path-based routing, anything sitting behind another layer that decodes %2F (common in microservice meshes).

Impact

Any HTTP path reachable from the Nitro server to the upstream could be requested, regardless of the configured /** scope. In typical deployments (API gateway, BFF, microservice proxy) this could expose internal admin endpoints, secrets endpoints, or other services the developer believed the scope rule fenced off.

Patched versions

Upgrade to one of:

2.13.4 or later (https://github.com/nitrojs/nitro/pull/4223)
3.0.260429-beta or later (https://github.com/nitrojs/nitro/pull/4222)

The fix canonicalizes the incoming pathname before building the upstream URL and rejects requests with 400 Bad Request if the resolved path would escape the rule's base. The bytes forwarded upstream are unchanged when the request is allowed.

Note: the fix assumes the upstream does not double-decode percent-encoding. If your upstream decodes twice (%252F → %2F → /), it remains your responsibility to harden it. Single-decode is standard.

Credits

Reported by @mHe4am (@he4am on HackerOne) via the Vercel Open Source program.

Severity

5.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "nitro"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.0.260429-beta"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "nitropack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.13.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44373"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-06T23:01:27Z",
    "nvd_published_at": "2026-05-13T21:16:48Z",
    "severity": "MODERATE"
  },
  "details": "A proxy route rule like:\n\n```ts\nrouteRules: {\n  \"/api/orders/**\": { proxy: { to: \"http://upstream/orders/**\" } }\n}\n```\n\nis intended to limit the proxy to URLs under `/api/orders/`. Before the patch, an attacker could bypass that scope by sending percent-encoded path traversal (`..%2f`) in the URL, causing Nitro to forward a request that the upstream resolved outside the configured scope. Example exploit:\n\n```\nGET /api/orders/..%2fadmin%2fconfig.json\n```\n\nNitro sees `..%2f` as opaque characters at match time, the `/api/orders/**` rule matched, and the raw path was forwarded to the upstream as `/orders/..%2fadmin/config.json`. An upstream that decodes `%2F` to  `/` then resolved `..` and can serve `/admin/config.json` outside the intended scope.\n\n### Are you affected?\n\nUsers may be affected if **ALL** of the following are true:\n\n1. Their project uses Nitro\u0027s `routeRules` with a `proxy` entry (`{ proxy: { to: \"...\" } }`).\n2. The proxy `to` value uses a `/**` wildcard suffix to forward sub-paths.\n3. The **upstream** behind the proxy decodes `%2F` as `/` before routing or filesystem lookup.\n4. Proxy route rules are _not_ handled natively at CDN (nitro v3 and vercel)\n\nWhether the bypass actually leaks data depends on the upstream. Modern JS frameworks keep `%2F` opaque per RFC 3986 and are safe by construction. \n\n- **Safe examples:** H3 v2, Express v5, Hono v4 \u2014 modern JS frameworks keep `%2F` opaque per RFC 3986.\n- **Vulnerable examples:** naive imlementations that decodes the URL, static file servers, CGI dispatchers, Python `os.path`-based routing, anything sitting behind another layer that decodes `%2F` (common in microservice meshes).\n\n## Impact\n\nAny HTTP path reachable from the Nitro server to the upstream could be requested, regardless of the configured `/**` scope. In typical deployments (API gateway, BFF, microservice proxy) this could expose internal admin endpoints, secrets endpoints, or other services the developer believed the scope rule fenced off.\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 (https://github.com/nitrojs/nitro/pull/4223) \n- [3.0.260429-beta](https://github.com/nitrojs/nitro/releases/tag/v3.0.260429-beta) or later (https://github.com/nitrojs/nitro/pull/4222)\n\nThe fix canonicalizes the incoming pathname before building the upstream URL and rejects requests with `400 Bad Request` if the resolved path would escape the rule\u0027s base. The bytes forwarded upstream are unchanged when the request is allowed.\n\n\u003e Note: the fix assumes the upstream does not double-decode percent-encoding. If your upstream decodes twice (`%252F \u2192 %2F \u2192 /`), it remains your responsibility to harden it. **Single-decode is standard**.\n\n## Credits\n\nReported by [@mHe4am](https://github.com/mHe4am) ([@he4am on HackerOne](https://hackerone.com/he4am)) via the [Vercel Open Source](https://hackerone.com/vercel-open-source?type=team) program.",
  "id": "GHSA-5w89-w975-hf9q",
  "modified": "2026-05-14T20:42:49Z",
  "published": "2026-05-06T23:01:27Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nitrojs/nitro/security/advisories/GHSA-5w89-w975-hf9q"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44373"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nitrojs/nitro/pull/4222"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nitrojs/nitro/pull/4223"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nitrojs/nitro"
    },
    {
      "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Nitro has a proxy scope bypass via percent-encoded path traversal in `routeRules`"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

Publication & reservation Sightings KEV catalogs Other timestamps

Loading timeline…

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-44373 (GCVE-0-2026-44373)

FKIE_CVE-2026-44373

GHSA-5W89-W975-HF9Q

Are you affected?

Impact

Patched versions

Credits

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour