CVE-2026-42554
MEDIUM
MEDIUM
Priority: 0.01
BB Relevance:
61/100
Published: 2026-05-11
Modified: 2026-10-26
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
Passive
S:
X
AT:
None
VC:
None
VI:
None
VA:
None
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.
Weakness Classification (1)
References & Advisories (1)
Exploit
Mitigation
Vendor Advisory