Ecosyste.ms: Advisories

Security Advisories: GSA_kwCzR0hTQS0zcTVwLTM1NTgtMzY0Zs4AA1xI

Fiber unauthorized access vulnerability in `ctx.IsFromLocal()`

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():

// IPs returns a string slice of IP addresses specified in the X-Forwarded-For request header.
// When IP validation is enabled, only valid IPs are returned.
func (c *Ctx) IPs() []string {
    return c.extractIPsFromHeader(HeaderXForwardedFor)
}

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

Permalink: https://github.com/advisories/GHSA-3q5p-3558-364f
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS0zcTVwLTM1NTgtMzY0Zs4AA1xI
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: 8 months ago
Updated: 6 months ago

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

Identifiers: GHSA-3q5p-3558-364f, CVE-2023-41338
References:

• https://github.com/gofiber/fiber/security/advisories/GHSA-3q5p-3558-364f
• https://github.com/gofiber/fiber/commit/b8c9ede6efa231116c4bd8bb9d5e03eac1cb76dc
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For
• https://nvd.nist.gov/vuln/detail/CVE-2023-41338
• https://docs.gofiber.io/api/ctx#isfromlocal
• https://github.com/advisories/GHSA-3q5p-3558-364f

Repository: https://github.com/gofiber/fiber
Blast Radius: 19.7

Affected Packages