🛡️ CVE-2026-42554
🟡 CVSS 6.1 — Medium ⚠️ Exploit Public CWE-79 NVD
6.1
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Fiber is a web framework for Go. Prior to 2.52.12 and 3.1.0, Cross-Site Scripting vulnerability in Go Fiber allows a remote attacker to inject arbitrary HTML/JavaScript by supplying Accept: text/html on any request whose handler passes attacker-influenced data to the AutoFormat() feature. The developer opts into content negotiation by calling AutoFormat(), but does not opt into raw HTML emission for a particular request; Fiber chooses that branch from attacker-controlled Accept. The html branch is the sole outlier in a method whose name (AutoFormat) and symmetrical structure actively telegraph "safe, format-agnostic reply." This vulnerability is fixed in 2.52.12 and 3.1.0.

Details

Severity MEDIUM
CVSS Score 6.1
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CWE CWE-79
Public Exploit ⚠️ Yes
Source NVD
Published 2026-05-11
Updated 2026-06-02
Modified 2026-05-18
Fix URL N/A

Affected Packages

Software From version Fixed in
fiber 3.0.0 3.1.0
github.com/gofiber/fiber/v2 — —
github.com/gofiber/fiber/v3 — —
unknown — —

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