{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-56865", "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc", "state": "PUBLISHED", "assignerShortName": "Go", "dateReserved": "2026-06-23T15:10:49.354Z", "datePublished": "2026-08-13T21:58:53.475Z", "dateUpdated": "2026-08-14T15:34:17.235Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc", "shortName": "Go", "dateUpdated": "2026-08-13T21:58:53.475Z"}, "title": "Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog", "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"}], "affected": [{"vendor": "Go toolchain", "product": "cmd/go", "collectionURL": "https://pkg.go.dev", "packageName": "cmd/go", "versions": [{"version": "0", "lessThan": "1.25.13", "status": "affected", "versionType": "semver"}, {"version": "1.26.0-0", "lessThan": "1.26.6", "status": "affected", "versionType": "semver"}, {"version": "1.27.0-0", "lessThan": "1.27.0-rc.3", "status": "affected", "versionType": "semver"}], "defaultStatus": "unaffected"}, {"vendor": "golang.org/x/mod", "product": "golang.org/x/mod/sumdb/tlog", "collectionURL": "https://pkg.go.dev", "packageName": "golang.org/x/mod/sumdb/tlog", "versions": [{"version": "0", "lessThan": "0.40.0", "status": "affected", "versionType": "semver"}], "programRoutines": [{"name": "tileHashReader.ReadHashes"}], "defaultStatus": "unaffected"}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "CWE-347: Improper Verification of Cryptographic Signature"}]}], "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"}], "credits": [{"lang": "en", "value": "Filippo Valsorda (Geomys)"}], "x_gcve": [{"vulnId": "CVE-2026-56865", "recordType": "advisory"}]}, "adp": [{"problemTypes": [{"descriptions": [{"type": "CWE", "cweId": "CWE-347", "lang": "en", "description": "CWE-347 Improper Verification of Cryptographic Signature"}]}], "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.4, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-08-14T15:33:28.143873Z", "id": "CVE-2026-56865", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-08-14T15:34:17.235Z"}}]}, "vulnerability-lookup:meta": {"epss": {"cve": "CVE-2026-56865", "date": "2026-10-27", "epss": "0.00129", "percentile": "0.02533"}, "microsoft_vex": {"current_release_date": "2026-09-24T02:38:48.000Z", "cve": "CVE-2026-56865", "id": "msrc_CVE-2026-56865", "initial_release_date": "2026-08-20T22:00:40.000Z", "product_status:fixed": "1", "product_status:known_affected": "4", "product_status:known_not_affected": "4", "source": "Microsoft CSAF VEX", "status": "final", "title": "Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog", "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-56865.json", "version": "6"}, "nvd": "{\"cve\":{\"id\":\"CVE-2026-56865\",\"sourceIdentifier\":\"security@golang.org\",\"published\":\"2026-08-13T22:17:22.797\",\"lastModified\":\"2026-09-03T16:37:52.170\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"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\"}],\"affected\":[{\"source\":\"security@golang.org\",\"affectedData\":[{\"vendor\":\"Go toolchain\",\"product\":\"cmd/go\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://pkg.go.dev\",\"packageName\":\"cmd/go\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"1.25.13\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"1.26.0-0\",\"lessThan\":\"1.26.6\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"1.27.0-0\",\"lessThan\":\"1.27.0-rc.3\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"golang.org/x/mod\",\"product\":\"golang.org/x/mod/sumdb/tlog\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://pkg.go.dev\",\"packageName\":\"golang.org/x/mod/sumdb/tlog\",\"programRoutines\":[{\"name\":\"tileHashReader.ReadHashes\"}],\"versions\":[{\"version\":\"0\",\"lessThan\":\"0.40.0\",\"versionType\":\"semver\",\"status\":\"affected\"}]}]}],\"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\"}}]},\"weaknesses\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-347\"}]}],\"references\":[{\"url\":\"https://go.dev/cl/814960\",\"source\":\"security@golang.org\"},{\"url\":\"https://go.dev/cl/815020\",\"source\":\"security@golang.org\"},{\"url\":\"https://go.dev/issue/80744\",\"source\":\"security@golang.org\"},{\"url\":\"https://groups.google.com/g/golang-announce/c/94pEornpRlI\",\"source\":\"security@golang.org\"},{\"url\":\"https://pkg.go.dev/vuln/GO-2026-6179\",\"source\":\"security@golang.org\"}]}}", "redhat_vex": {"aggregate_severity": "Important", "current_release_date": "2026-10-08T22:39:39+00:00", "cve": "CVE-2026-56865", "id": "CVE-2026-56865", "initial_release_date": "2026-08-13T21:58:53.475000+00:00", "product_status:fixed": "16", "product_status:known_affected": "8", "product_status:known_not_affected": "130", "source": "Red Hat CSAF VEX", "status": "final", "title": "golang.org/x/mod/sumdb/tlog: golang.org/x/mod/sumdb/tlog: Supply chain compromise via transparency log tile verification bypass", "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-56865.json", "version": "3"}, "vulnrichment": {"containers": "{\"cna\": {\"providerMetadata\": {\"orgId\": \"1bb62c36-49e3-4200-9d77-64a1400537cc\", \"shortName\": \"Go\", \"dateUpdated\": \"2026-08-13T21:58:53.475Z\"}, \"title\": \"Fix transparency log tile verification bypass in golang.org/x/mod/sumdb/tlog\", \"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\"}], \"affected\": [{\"vendor\": \"Go toolchain\", \"product\": \"cmd/go\", \"collectionURL\": \"https://pkg.go.dev\", \"packageName\": \"cmd/go\", \"versions\": [{\"version\": \"0\", \"lessThan\": \"1.25.13\", \"status\": \"affected\", \"versionType\": \"semver\"}, {\"version\": \"1.26.0-0\", \"lessThan\": \"1.26.6\", \"status\": \"affected\", \"versionType\": \"semver\"}, {\"version\": \"1.27.0-0\", \"lessThan\": \"1.27.0-rc.3\", \"status\": \"affected\", \"versionType\": \"semver\"}], \"defaultStatus\": \"unaffected\"}, {\"vendor\": \"golang.org/x/mod\", \"product\": \"golang.org/x/mod/sumdb/tlog\", \"collectionURL\": \"https://pkg.go.dev\", \"packageName\": \"golang.org/x/mod/sumdb/tlog\", \"versions\": [{\"version\": \"0\", \"lessThan\": \"0.40.0\", \"status\": \"affected\", \"versionType\": \"semver\"}], \"programRoutines\": [{\"name\": \"tileHashReader.ReadHashes\"}], \"defaultStatus\": \"unaffected\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"description\": \"CWE-347: Improper Verification of Cryptographic Signature\"}]}], \"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\"}], \"credits\": [{\"lang\": \"en\", \"value\": \"Filippo Valsorda (Geomys)\"}]}, \"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 8.4, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-56865\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-14T15:33:28.143873Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-347\", \"description\": \"CWE-347 Improper Verification of Cryptographic Signature\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-14T15:34:11.473Z\"}}]}", "cveMetadata": "{\"cveId\": \"CVE-2026-56865\", \"assignerOrgId\": \"1bb62c36-49e3-4200-9d77-64a1400537cc\", \"state\": \"PUBLISHED\", \"assignerShortName\": \"Go\", \"dateReserved\": \"2026-06-23T15:10:49.354Z\", \"datePublished\": \"2026-08-13T21:58:53.475Z\", \"dateUpdated\": \"2026-08-14T15:34:17.235Z\"}", "dataType": "CVE_RECORD", "dataVersion": "5.2"}}}