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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-qjv7-627w-8qjv Fiber vulnerable to XSS in AutoFormat Content Negotiation
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 18 May 2026 17:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:gofiber:fiber:*:*:*:*:*:go:*:*
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}


Fri, 15 May 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 12 May 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Gofiber
Gofiber fiber
Vendors & Products Gofiber
Gofiber fiber

Mon, 11 May 2026 22:30:00 +0000

Type Values Removed Values Added
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.
Title Fiber: XSS in AutoFormat Content Negotiation
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-15T18:24:38.300Z

Reserved: 2026-04-28T16:56:50.191Z

Link: CVE-2026-42554

cve-icon Vulnrichment

Updated: 2026-05-15T18:24:34.549Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-11T23:19:48.083

Modified: 2026-05-18T16:50:44.640

Link: CVE-2026-42554

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-12T00:15:07Z

Weaknesses