CVE-2026-42554

6.1 MEDIUM

Fiber is a web framework for Go

Published: 2026-05-11 · Last updated: 2026-05-18

Severity and scoring

CVSS: 6.1 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CWE: CWE-79

Affected products

Vendor	Product
gofiber	fiber

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.

Source: NVD

References

[NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-42554
[Vendor advisory]https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv
[Vendor advisory]https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv

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