{"api_version":"1","generated_at":"2026-08-14T17:46:26+00:00","cve":"CVE-2026-56865","urls":{"html":"https://cve.report/CVE-2026-56865","api":"https://cve.report/api/cve/CVE-2026-56865.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-56865","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-56865"},"summary":{"title":"Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog","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","state":"PUBLISHED","assigner":"Go","published_at":"2026-08-13 22:17:22","updated_at":"2026-08-14 16:16:57"},"problem_types":["CWE-347","CWE-347: Improper Verification of Cryptographic Signature","CWE-347 CWE-347 Improper Verification of Cryptographic Signature"],"metrics":[{"version":"3.1","source":"ADP","type":"DECLARED","score":"8.4","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":8.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}},{"version":"3.1","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","score":"8.4","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.4,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}}],"references":[{"url":"https://go.dev/issue/80744","name":"https://go.dev/issue/80744","refsource":"security@golang.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://groups.google.com/g/golang-announce/c/94pEornpRlI","name":"https://groups.google.com/g/golang-announce/c/94pEornpRlI","refsource":"security@golang.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://go.dev/cl/814960","name":"https://go.dev/cl/814960","refsource":"security@golang.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://go.dev/cl/815020","name":"https://go.dev/cl/815020","refsource":"security@golang.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://pkg.go.dev/vuln/GO-2026-6179","name":"https://pkg.go.dev/vuln/GO-2026-6179","refsource":"security@golang.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-56865","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56865","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Go toolchain","product":"cmd/go","version":"affected 1.25.13 semver","platforms":[]},{"source":"CNA","vendor":"Go toolchain","product":"cmd/go","version":"affected 1.26.0-0 1.26.6 semver","platforms":[]},{"source":"CNA","vendor":"Go toolchain","product":"cmd/go","version":"affected 1.27.0-0 1.27.0-rc.3 semver","platforms":[]},{"source":"CNA","vendor":"golang.org/x/mod","product":"golang.org/x/mod/sumdb/tlog","version":"affected 0.40.0 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"Filippo Valsorda (Geomys)","lang":"en"}],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":8.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}},{"other":{"content":{"id":"CVE-2026-56865","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","timestamp":"2026-08-14T15:33:28.143873Z","version":"2.0.3"},"type":"ssvc"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-347","description":"CWE-347 Improper Verification of Cryptographic Signature","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-08-14T15:34:17.235Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"collectionURL":"https://pkg.go.dev","defaultStatus":"unaffected","packageName":"cmd/go","product":"cmd/go","vendor":"Go toolchain","versions":[{"lessThan":"1.25.13","status":"affected","version":"0","versionType":"semver"},{"lessThan":"1.26.6","status":"affected","version":"1.26.0-0","versionType":"semver"},{"lessThan":"1.27.0-rc.3","status":"affected","version":"1.27.0-0","versionType":"semver"}]},{"collectionURL":"https://pkg.go.dev","defaultStatus":"unaffected","packageName":"golang.org/x/mod/sumdb/tlog","product":"golang.org/x/mod/sumdb/tlog","programRoutines":[{"name":"tileHashReader.ReadHashes"}],"vendor":"golang.org/x/mod","versions":[{"lessThan":"0.40.0","status":"affected","version":"0","versionType":"semver"}]}],"credits":[{"lang":"en","value":"Filippo Valsorda (Geomys)"}],"descriptions":[{"lang":"en","value":"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"}],"problemTypes":[{"descriptions":[{"description":"CWE-347: Improper Verification of Cryptographic Signature","lang":"en"}]}],"providerMetadata":{"dateUpdated":"2026-08-13T21:58:53.475Z","orgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","shortName":"Go"},"references":[{"url":"https://go.dev/issue/80744"},{"url":"https://groups.google.com/g/golang-announce/c/94pEornpRlI"},{"url":"https://go.dev/cl/814960"},{"url":"https://go.dev/cl/815020"},{"url":"https://pkg.go.dev/vuln/GO-2026-6179"}],"title":"Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog"}},"cveMetadata":{"assignerOrgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","assignerShortName":"Go","cveId":"CVE-2026-56865","datePublished":"2026-08-13T21:58:53.475Z","dateReserved":"2026-06-23T15:10:49.354Z","dateUpdated":"2026-08-14T15:34:17.235Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-13 22:17:22","lastModifiedDate":"2026-08-14 16:16:57","problem_types":["CWE-347","CWE-347: Improper Verification of Cryptographic Signature","CWE-347 CWE-347 Improper Verification of Cryptographic Signature"],"metrics":{"cvssMetricV31":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.4,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2.5,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-08-14T15:33:28.143873Z","id":"CVE-2026-56865","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"56865","Ordinal":"1","Title":"Fix transparency log tile verification bypass in golang.org/x/mo","CVE":"CVE-2026-56865","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"56865","Ordinal":"1","NoteData":"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","Type":"Description","Title":"Fix transparency log tile verification bypass in golang.org/x/mo"}]}}}