gofiber up to 2.52.12/3.0.x AutoFormat cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, has been found in gofiber fiber up to 2.52.12/3.0.x. The affected element is the function AutoFormat. This manipulation causes cross site scripting. This vulnerability is tracked as CVE-2026-42554. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in gofiber fiber up to 2.52.12/3.0.x. It has been declared as problematic. Affected by this vulnerability is the function AutoFormat. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-42554 since 04/28/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 2.52.13 or 3.1.0 eliminates this vulnerability.

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Productinfo

Vendor

• gofiber

Name

• fiber

Version

• 2.52.0
• 2.52.1
• 2.52.2
• 2.52.3
• 2.52.4
• 2.52.5
• 2.52.6
• 2.52.7
• 2.52.8
• 2.52.9
• 2.52.10
• 2.52.11
• 2.52.12
• 3.0

Website

• Product: https://github.com/gofiber/fiber/

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