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

Moderate severity GitHub Reviewed Published Sep 8, 2023 in gofiber/fiber • Updated Nov 5, 2023

Package

gomod github.com/gofiber/fiber (Go)

Affected versions

<= 1.14.6

Patched versions

None
gomod github.com/gofiber/fiber/v2 (Go)
< 2.49.2
2.49.2

Description

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:

References

@ReneWerner87 ReneWerner87 published to gofiber/fiber Sep 8, 2023
Published to the GitHub Advisory Database Sep 8, 2023
Reviewed Sep 8, 2023
Published by the National Vulnerability Database Sep 8, 2023
Last updated Nov 5, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

0.084%
(37th percentile)

Weaknesses

CVE ID

CVE-2023-41338

GHSA ID

GHSA-3q5p-3558-364f

Source code

Credits

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