CVE-2026-42554
Fiber: XSS in AutoFormat Content Negotiation
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.
| CWE | CWE-79 |
| Vendor | gofiber |
| Product | fiber |
| Published | May 11, 2026 |
Get instant alerts for gofiber fiber
Be the first to know when new unknown vulnerabilities affecting gofiber fiber are published — delivered to Slack, Telegram or Discord.