{"cve":"CVE-2026-56865","nvd":{"published":"2026-08-13T22:17:22.797","modified":"2026-09-03T16:37:52.170","status":"Awaiting Analysis","description":"A malicious GOPROXY was previously capable of forging up to two sumdb tiles that allow for a requested module to bypass the GOSUMDB check and persist attacker-controlled module content to a local Go module cache. This attack allows for a malicious GOPROXY to serve malicious module content that cannot be detected by evaluating the transparency log. All tiles are now correctly verified against their parents. In order to determine if you have been affected:   rm -r go.sum go.work.sum vendor/ && go mod tidy","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.4},"cwes":["CWE-347"],"references":["https://go.dev/cl/814960","https://go.dev/cl/815020","https://go.dev/issue/80744","https://groups.google.com/g/golang-announce/c/94pEornpRlI","https://pkg.go.dev/vuln/GO-2026-6179"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:48:17.459049833+00:00"},"epss":{"cve":"CVE-2026-56865","score":0.00129,"percentile":0.02533,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GO-2026-6179","url":"https://osv.dev/vulnerability/GO-2026-6179","summary":"Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog","modified":"2026-08-19T12:25:40.780492871Z","packages":[{"ecosystem":"Go","name":"toolchain","purl":"pkg:golang/toolchain","ranges":["<1.25.13",">=1.26.0-0 <1.26.6",">=1.27.0-0 <1.27.0-rc.3"],"fixed":["1.25.13","1.26.6","1.27.0-rc.3"]},{"ecosystem":"Go","name":"golang.org/x/mod","purl":"pkg:golang/golang.org/x/mod","ranges":["<0.40.0"],"fixed":["0.40.0"]}]}],"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."]}