Home

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.

PUBLISHED Reserved 2026-04-28 | Published 2026-05-11 | Updated 2026-05-15 | Assigner GitHub_M




MEDIUM: 5.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Problem types

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Product status

< 2.52.13
affected

>= 3.0.0-beta.2, < 3.1.0
affected

References

github.com/.../fiber/security/advisories/GHSA-qjv7-627w-8qjv exploit

github.com/.../fiber/security/advisories/GHSA-qjv7-627w-8qjv

cve.org (CVE-2026-42554)

nvd.nist.gov (CVE-2026-42554)

Download JSON