{"id":"GHSA-3q5p-3558-364f","summary":"Fiber unauthorized access vulnerability in `ctx.IsFromLocal()`","details":"### Impact\nThis vulnerability can be categorized as a security misconfiguration. It impacts users of our project who rely on the [ctx.IsFromLocal()](https://docs.gofiber.io/api/ctx#isfromlocal) method to restrict access to localhost requests. If exploited, it could allow unauthorized access to resources intended only for localhost.\n\nIn it's implementation it uses c.IPs():\n\n```go\n// IPs returns a string slice of IP addresses specified in the X-Forwarded-For request header.\n// When IP validation is enabled, only valid IPs are returned.\nfunc (c *Ctx) IPs() []string {\n    return c.extractIPsFromHeader(HeaderXForwardedFor)\n}\n```\n\nThereby, setting `X-Forwarded-For: 127.0.0.1` in a request from a foreign host, will result in true for [ctx.IsFromLocal()](https://docs.gofiber.io/api/ctx#isfromlocal) \n\n### Patches\nThis issue has been patched in `v2.49.2` with commit [b8c9ede6efa231116c4bd8bb9d5e03eac1cb76dc](https://github.com/gofiber/fiber/commit/b8c9ede6efa231116c4bd8bb9d5e03eac1cb76dc)\n\n### Workarounds\nCurrently, there are no known workarounds to remediate this vulnerability without upgrading to the patched version. We strongly advise users to apply the patch as soon as it is released.\n\n### References\nFor further information and context regarding this security issue, please refer to the following resources:\n\n- [Mozilla Developer Network - X-Forwarded-For](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For)\n\n","aliases":["CVE-2023-41338","GO-2023-2052"],"modified":"2026-09-10T03:50:03.184878597Z","published":"2023-09-08T13:27:21Z","database_specific":{"nvd_published_at":"2023-09-08T19:15:43Z","cwe_ids":["CWE-670"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2023-09-08T13:27:21Z"},"references":[{"type":"WEB","url":"https://github.com/gofiber/fiber/security/advisories/GHSA-3q5p-3558-364f"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-41338"},{"type":"WEB","url":"https://github.com/gofiber/fiber/commit/b8c9ede6efa231116c4bd8bb9d5e03eac1cb76dc"},{"type":"WEB","url":"https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For"},{"type":"WEB","url":"https://docs.gofiber.io/api/ctx#isfromlocal"},{"type":"PACKAGE","url":"https://github.com/gofiber/fiber"}],"affected":[{"package":{"name":"github.com/gofiber/fiber","ecosystem":"Go","purl":"pkg:golang/github.com/gofiber/fiber"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"last_affected":"1.14.6"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2023/09/GHSA-3q5p-3558-364f/GHSA-3q5p-3558-364f.json"}},{"package":{"name":"github.com/gofiber/fiber/v2","ecosystem":"Go","purl":"pkg:golang/github.com/gofiber/fiber/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.49.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2023/09/GHSA-3q5p-3558-364f/GHSA-3q5p-3558-364f.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"}]}