{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-62949", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-07-14T22:32:17.731Z", "datePublished": "2026-09-16T20:00:46.657Z", "dateUpdated": "2026-09-17T15:01:48.863Z"}, "containers": {"cna": {"title": "AsyncSSH: asyncio event-loop freeze via SSH maximum packet size = 0 in SSH_MSG_CHANNEL_OPEN / OPEN_CONFIRMATION", "problemTypes": [{"descriptions": [{"cweId": "CWE-835", "lang": "en", "description": "CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}}], "references": [{"name": "https://github.com/ronf/asyncssh/security/advisories/GHSA-rw4j-r22c-9gc3", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/ronf/asyncssh/security/advisories/GHSA-rw4j-r22c-9gc3"}, {"name": "https://github.com/ronf/asyncssh/commit/756cbae5350789ce9735f15f704bae9b5a3608b8", "tags": ["x_refsource_MISC"], "url": "https://github.com/ronf/asyncssh/commit/756cbae5350789ce9735f15f704bae9b5a3608b8"}, {"name": "https://github.com/ronf/asyncssh/commit/9c354270c009285525e126721e8ed5fbed1f8a67", "tags": ["x_refsource_MISC"], "url": "https://github.com/ronf/asyncssh/commit/9c354270c009285525e126721e8ed5fbed1f8a67"}, {"name": "https://github.com/ronf/asyncssh/releases/tag/v2.24.0", "tags": ["x_refsource_MISC"], "url": "https://github.com/ronf/asyncssh/releases/tag/v2.24.0"}], "affected": [{"vendor": "ronf", "product": "asyncssh", "versions": [{"version": "< 2.24.0", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-09-16T20:00:46.657Z"}, "descriptions": [{"lang": "en", "value": "AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Prior to 2.24.0, _process_channel_open and _process_channel_open_confirmation in asyncssh/connection.py accept a peer-supplied send_pktsize value of zero. When channel data reaches SSHChannel._flush_send_buf in asyncssh/channel.py, the zero value causes each loop iteration to slice and remove zero bytes without reducing the send window, leaving the synchronous loop permanently true with no await point. A malicious SSH server can trigger the client path through SSH_MSG_CHANNEL_OPEN_CONFIRMATION before the first channel write, while an authenticated client can trigger the server path through SSH_MSG_CHANNEL_OPEN and freeze every current and future connection handled by the process. This vulnerability is fixed in 2.24.0."}], "source": {"advisory": "GHSA-rw4j-r22c-9gc3", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-09-17T15:01:41.382412Z", "id": "CVE-2026-62949", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-17T15:01:48.863Z"}}]}}

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{"bugzilla": {"description": "asyncssh: AsyncSSH: Denial of Service via zero-sized SSH packets", "id": "2535643", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2535643"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-835", "details": ["A flaw was found in AsyncSSH, a Python package for SSHv2 protocol implementation. A malicious SSH server or an authenticated client can exploit this vulnerability by sending a specially crafted SSH packet with a zero-sized maximum packet size. This can cause the AsyncSSH event loop to freeze, leading to a Denial of Service (DoS) for all current and future connections handled by the process."], "name": "CVE-2026-62949", "package_state": [{"cpe": "cpe:/a:redhat:ceph_storage:7", "fix_state": "Fix deferred", "package_name": "rhceph/rhceph-7-rhel9", "product_name": "Red Hat Ceph Storage 7"}, {"cpe": "cpe:/a:redhat:ceph_storage:8", "fix_state": "Fix deferred", "package_name": "rhceph/rhceph-8-rhel9", "product_name": "Red Hat Ceph Storage 8"}, {"cpe": "cpe:/a:redhat:ceph_storage:9", "fix_state": "Out of support scope", "package_name": "rhceph/rhceph-9-rhel9", "product_name": "Red Hat Ceph Storage 9"}], "public_date": "2026-09-16T20:00:46Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-62949\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-62949\nhttps://github.com/ronf/asyncssh/commit/756cbae5350789ce9735f15f704bae9b5a3608b8\nhttps://github.com/ronf/asyncssh/commit/9c354270c009285525e126721e8ed5fbed1f8a67\nhttps://github.com/ronf/asyncssh/releases/tag/v2.24.0\nhttps://github.com/ronf/asyncssh/security/advisories/GHSA-rw4j-r22c-9gc3"], "threat_severity": "Moderate"}

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