Vulnerability · Published Jul 8, 2026 · Assigned by GitHub_M

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

Medium 5.3

In plain English

A medium-severity security flaw in fiber from gofiber. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.5%top 55.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/gofiber/fiber/v3	3.3.0	GHSA-g5vh-55hw-rxm8
Go	github.com/gofiber/fiber/v3	3.3.0	GO-2026-5886
Ubuntu:26.10	golang-github-gofiber-fiber	no fix listed	UBUNTU-CVE-2026-44332

Affected products (as reported)

Vendor	Product	Versions
gofiber	fiber	< 3.3.0

Weakness: CWE-203 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

References

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