{"id":"CVE-2026-42554","summary":"Fiber: XSS in AutoFormat Content Negotiation","details":"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.","aliases":["GHSA-qjv7-627w-8qjv"],"modified":"2026-07-15T01:49:07.771719071Z","published":"2026-05-11T21:47:17.133Z","related":["CGA-7m94-w8fx-6g5v"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-79"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42554.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42554.json"},{"type":"ADVISORY","url":"https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42554"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/gofiber/fiber","events":[{"introduced":"0"},{"fixed":"6cba19533db837ae5c9c0f5941dec5dae019e18c"},{"introduced":"f8f34f642fb3682c341ede7816e7cf861aa7df89"},{"fixed":"3c24ebefe5009e88f9f9258b472e8021160179bf"}],"database_specific":{"cpe":"cpe:2.3:a:gofiber:fiber:*:*:*:*:*:go:*:*","extracted_events":[{"introduced":"0"},{"fixed":"2.52.12"},{"introduced":"3.0.0"},{"fixed":"3.1.0"}],"source":"CPE_RANGE"}}],"versions":["v2.52.11","v2.52.10","v3.0.0-rc.2","v3.0.0-rc.1","v3.0.0-beta.5","v2.52.9","v2.52.8","v2.52.7","v2.52.6","v3.0.0-beta.4","v2.52.5","v3.0.0-beta.3","v2.52.4","v2.52.3","v2.52.2","v2.52.1","v2.52.0","v2.51.0","v2.50.0","v2.49.2","v2.49.1","v2.49.0","v2.48.0","v2.47.0","v2.46.0","v2.45.0","v2.44.0","v2.43.0","v2.42.0","v2.41.0","v2.40.1","v2.40.0","v2.39.0","v2.38.1","v2.38.0","v2.37.1","v2.37.0","v2.37.0-rc.1","v2.36.0","v2.35.0","v2.34.1","v2.34.0","v2.34.0-rc.1","v2.33.0","v2.32.0","v2.31.0","v2.30.0","v2.29.0","v2.28.0","v2.27.0","v2.26.0","v2.25.0","v2.24.0","v2.23.0","v2.22.0","v2.21.0","v2.20.2","v2.20.1","v2.20.0","v2.19.0","v2.18.0","v2.17.0","v2.16.0","v2.15.0","v2.14.0","v2.13.0","v2.12.0","v2.11.0","v2.10.0","v2.9.0","v2.8.0","v2.7.1","v2.7.0","v2.6.0","v2.4.1","v2.5.0","v2.4.0","v2.3.3","v2.3.2","v2.3.1","v2.3.0","v2.2.5","v2.2.4","v2.2.3","v2.2.2","v2.2.1","v2.2.0","v2.1.4","v2.1.3","v2.1.2","v1.14.6","v2.1.1","v2.1.0","v2.0.6","v2.0.5","v2.0.4","v2.0.3","v2.0.2","v2.0.1","v2.0.0","v1.14.5","v1.14.4","v1.14.3","v1.14.2","v1.14.1","v1.13.3","v1.13.2","v1.13.1","v1.13.0","v1.12.6","v1.12.5","v1.12.4","v1.12.3","v1.12.2","v1.12.1","v1.12.0","v1.11.1","v1.11.0","v1.10.5","v1.10.0","v1.9.6","v1.9.3","v1.9.2","v1.9.1","v1.9.0","v1.8.43","v1.8.42","v1.8.41","v1.8.4","v1.8.3","v1.8.2","v1.8.1","v1.8.0","v1.7.1","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42554.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"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"}]}