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CVE-2026-42554

Fiber: XSS in AutoFormat Content Negotiation PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
gofiber / fiberaffected < 2.52.13; affected >= 3.0.0-beta.2, < 3.1.0

CWE

CWE-79

References

ADP enrichment

CISA-ADP

No English description supplied.