Medium severity · published Jul 8, 2026
CVE-2026-44332
Fiber: Username Enumeration via Timing Oracle in BasicAuth Default Authorizer
5.3
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
fiber · gofiber
< 3.3.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44332
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-44332
Patch
https://github.com/gofiber/fiber/commit/c7ac00edd19f9669b1aebbec6e229658baaa059e
Issue Tracking
https://github.com/gofiber/fiber/pull/4245
Release Notes
https://github.com/gofiber/fiber/releases/tag/v3.3.0
Exploit
https://github.com/gofiber/fiber/security/advisories/GHSA-g5vh-55hw-rxm8
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