What’s Vulnerable › Vulnerabilities

CVE-2026-44332: Fiber: Username Enumeration via Timing Oracle in BasicAuth Default Authorizer

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-203

Description

Fiber is an Express inspired web framework written in Go. Prior to 3.3.0, the default Authorizer function in the BasicAuth middleware in middleware/basicauth/config.go uses short-circuit evaluation that skips password hash comparison for non-existent usernames, enabling reliable remote username enumeration through response timing differences. This issue is fixed in version 3.3.0.

Affected products

• gofiber fiber: before 3.3.0 — fixed in 3.3.0

How to fix

Upgrade to a fixed version: gofiber fiber 3.3.0. Check the vendor advisory for mitigations.

References

• https://github.com/gofiber/fiber/commit/c7ac00edd19f9669b1aebbec6e229658baaa059e
• https://github.com/gofiber/fiber/pull/4245
• https://github.com/gofiber/fiber/releases/tag/v3.3.0
• https://github.com/gofiber/fiber/security/advisories/GHSA-g5vh-55hw-rxm8

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