CVE-2026-42554

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.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv	Exploit Mitigation Vendor Advisory
https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv	Exploit Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:gofiber:fiber::::::go::*
	cpe:2.3:a:gofiber:fiber::::::go::*

History

18 May 2026, 16:50

Type	Values Removed	Values Added
References	~~() https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv -~~	() https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv - Exploit, Mitigation, Vendor Advisory
CPE		cpe:2.3:a:gofiber:fiber::::::go::*
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 6.1
First Time		Gofiber fiber Gofiber

15 May 2026, 19:16

Type	Values Removed	Values Added
References	~~() https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv -~~	() https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv -

11 May 2026, 23:19

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-05-11 23:19

Updated : 2026-05-18 16:50

NVD link : CVE-2026-42554

Mitre link : CVE-2026-42554

CVE.ORG link : CVE-2026-42554

JSON object : View

Products Affected

gofiber

fiber

CWE

CWE-79

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

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