{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-66034", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-07-23T20:45:17.816Z", "datePublished": "2026-07-24T16:42:18.764Z", "dateUpdated": "2026-07-25T10:30:09.019Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-07-25T10:30:09.019Z"}, "title": "libssh2 Heap Out-of-Bounds Read via publickey subsystem", "descriptions": [{"lang": "en", "value": "libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region."}], "tags": ["x_open-source"], "datePublic": "2026-07-04T00:00:00.000Z", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-125", "description": "Out-of-bounds Read", "type": "CWE"}, {"lang": "en", "cweId": "CWE-908", "description": "Use of Uninitialized Resource", "type": "CWE"}]}], "affected": [{"defaultStatus": "affected", "vendor": "libssh2", "product": "libssh2", "packageURL": "pkg:github/libssh2/libssh2", "repo": "https://github.com/libssh2/libssh2", "versions": [{"status": "affected", "version": "0", "versionType": "semver", "lessThanOrEqual": "1.11.1"}, {"status": "unaffected", "version": "a13bb6c773f0d55ad1628cede57e99803cd898d9", "versionType": "git"}]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 7.7, "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"}}, {"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH", "version": "3.1", "baseSeverity": "HIGH", "baseScore": 7.5, "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H"}}], "references": [{"url": "https://github.com/libssh2/libssh2/pull/2202", "name": "Pull Request", "tags": ["issue-tracking", "patch"]}, {"url": "https://github.com/libssh2/libssh2/commit/a13bb6c773f0d55ad1628cede57e99803cd898d9", "name": "Patch Commit", "tags": ["patch"]}, {"url": "https://www.vulncheck.com/advisories/libssh2-heap-out-of-bounds-read-via-publickey-subsystem", "tags": ["third-party-advisory"]}], "credits": [{"lang": "en", "value": "VladimirEliTokarev", "type": "finder"}], "source": {"discovery": "UNKNOWN"}, "x_generator": {"engine": "vulncheck"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-07-24T00:00:00+00:00", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3", "id": "CVE-2026-66034"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-25T03:55:51.727Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-66034", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-07-24T17:31:09.552541Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-24T17:31:12.343Z"}}], "cna": {"tags": ["x_open-source"], "title": "libssh2 Heap Out-of-Bounds Read via publickey subsystem", "source": {"discovery": "UNKNOWN"}, "credits": [{"lang": "en", "type": "finder", "value": "VladimirEliTokarev"}], "metrics": [{"format": "CVSS", "cvssV4_0": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 7.7, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "PASSIVE", "attackComplexity": "HIGH", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}, {"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "REQUIRED", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"repo": "https://github.com/libssh2/libssh2", "vendor": "libssh2", "product": "libssh2", "versions": [{"status": "affected", "version": "0", "versionType": "semver", "lessThanOrEqual": "1.11.1"}, {"status": "unaffected", "version": "a13bb6c773f0d55ad1628cede57e99803cd898d9", "versionType": "git"}], "packageURL": "pkg:github/libssh2/libssh2", "defaultStatus": "affected"}], "datePublic": "2026-07-04T00:00:00.000Z", "references": [{"url": "https://github.com/libssh2/libssh2/pull/2202", "name": "Pull Request", "tags": ["issue-tracking", "patch"]}, {"url": "https://github.com/libssh2/libssh2/commit/a13bb6c773f0d55ad1628cede57e99803cd898d9", "name": "Patch Commit", "tags": ["patch"]}, {"url": "https://www.vulncheck.com/advisories/libssh2-heap-out-of-bounds-read-via-publickey-subsystem", "tags": ["third-party-advisory"]}], "x_generator": {"engine": "vulncheck"}, "descriptions": [{"lang": "en", "value": "libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-125", "description": "Out-of-bounds Read"}, {"lang": "en", "type": "CWE", "cweId": "CWE-908", "description": "Use of Uninitialized Resource"}]}], "providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-07-25T10:30:09.019Z"}}}, "cveMetadata": {"cveId": "CVE-2026-66034", "state": "PUBLISHED", "dateUpdated": "2026-07-25T10:30:09.019Z", "dateReserved": "2026-07-23T20:45:17.816Z", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "datePublished": "2026-07-24T16:42:18.764Z", "assignerShortName": "VulnCheck"}, "dataVersion": "5.2"}

{}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.11.1]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "code_commit", "value": "a13bb6c773f0d55ad1628cede57e99803cd898d9"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "libssh2", "source": "cna", "vendor": "libssh2"}, "product": "libssh2", "vendor": "libssh2"}], "created": "2026-07-24T22:45:17.097593+00:00", "updated": "2026-07-24T22:45:17.097623+00:00", "vendors": ["libssh2", "libssh2$PRODUCT$libssh2"]}