Fiber unauthorized access vulnerability in ctx.IsFromLocal()

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2023-41338: 0.66% estimated exploitation activity in the next 30 days; percentile 51.43 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact This vulnerability can be categorized as a security misconfiguration. It impacts users of our project who rely on the ctx.IsFromLocal() method to restrict access to localhost requests. If exploited, it could allow unauthorized access to resources intended only for localhost. In it's implementation it uses c.IPs(): Thereby, setting X-Forwarded-For: 127.0.0.1 in a request from a foreign host, will result in true for ctx.IsFromLocal() Patches This issue has been patched in v2.49.2 with commit b8c9ede6efa231116c4bd8bb9d5e03eac1cb76dc Workarounds Currently, 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. References For further information and context regarding this security issue, please refer to the following resources: - Mozilla Developer Network - X-Forwarded-For

Published by the source

8 Sep 2023, 13:27 UTC

Last modified by the source

5 Nov 2023, 05:01 UTC

Source last checked

26 Oct 2026, 14:59 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3q5p-3558-364f

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# Patch Next advisory brief: CVE-2023-41338

Advisory: Fiber unauthorized access vulnerability in `ctx.IsFromLocal()`
IDs: CVE-2023-41338, GHSA-3q5p-3558-364f
Record: https://patchnext.com/advisories/cve-2023-41338 (revision 1, source checked 26 Oct 2026, 14:59 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/gofiber/fiber/v2 2.49.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/gofiber/fiber: affected <= 1.14.6
- Go github.com/gofiber/fiber/v2: affected < 2.49.2; fixed in 2.49.2

## Suggested inspection (read-only)
- Go github.com/gofiber/fiber: check the installed version with your package manager.
- Go github.com/gofiber/fiber/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/gofiber/fiber, github.com/gofiber/fiber/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3q5p-3558-364f (GitHub-reviewed advisory GHSA-3q5p-3558-364f lists affected ranges: Go github.com/gofiber/fiber >=0 =0 <2.49.2)

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