{"cve":"CVE-2026-42554","nvd":{"published":"2026-05-11T23:19:48.083","modified":"2026-10-26T18:10:00.173","status":"Analyzed","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.","cvss_v4":{"vector":"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","score":5.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1},"cwes":["CWE-79"],"references":["https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv","https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv"],"products":["gofiber:fiber"],"source":"nvd","synced_at":"2026-10-26T18:27:13.530666824+00:00"},"epss":{"cve":"CVE-2026-42554","score":0.00212,"percentile":0.11448,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-qjv7-627w-8qjv","url":"https://osv.dev/vulnerability/GHSA-qjv7-627w-8qjv","summary":"Fiber vulnerable to XSS in AutoFormat Content Negotiation","modified":"2026-09-10T03:50:47.332641426Z","packages":[{"ecosystem":"Go","name":"github.com/gofiber/fiber/v3","purl":"pkg:golang/github.com/gofiber/fiber/v3","ranges":["<3.2.0"],"fixed":["3.2.0"]},{"ecosystem":"Go","name":"github.com/gofiber/fiber/v2","purl":"pkg:golang/github.com/gofiber/fiber/v2","ranges":["<2.52.13"],"fixed":["2.52.13"]}]},{"id":"GO-2026-5585","url":"https://osv.dev/vulnerability/GO-2026-5585","summary":"Fiber vulnerable to XSS in AutoFormat Content Negotiation in github.com/gofiber/fiber","modified":"2026-07-24T19:00:24.231440095Z","packages":[{"ecosystem":"Go","name":"github.com/gofiber/fiber/v2","purl":"pkg:golang/github.com/gofiber/fiber/v2","ranges":["<2.52.13"],"fixed":["2.52.13"]},{"ecosystem":"Go","name":"github.com/gofiber/fiber/v3","purl":"pkg:golang/github.com/gofiber/fiber/v3","ranges":["<3.2.0"],"fixed":["3.2.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}