{"cve":{"cve_id":"CVE-2026-62949","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00389,"epss_percentile":0.31346,"epss_as_of":"2026-10-15","description":"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.","published_at":"2026-09-16T20:00:46.657000Z","last_modified_at":"2026-09-30T17:43:24.057000Z","cvss_v3_score":6.5,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvss_v3_severity":"MEDIUM","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-835"],"nvd_references":["https://github.com/ronf/asyncssh/security/advisories/GHSA-rw4j-r22c-9gc3","https://github.com/ronf/asyncssh/commit/756cbae5350789ce9735f15f704bae9b5a3608b8","https://github.com/ronf/asyncssh/commit/9c354270c009285525e126721e8ed5fbed1f8a67","https://github.com/ronf/asyncssh/releases/tag/v2.24.0"],"vuln_status":"Awaiting Analysis","trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-09-16T21:03:42.088887Z","updated_at":"2026-10-02T10:03:01.593453Z"},"effective_severity":"MEDIUM","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"L","value_label":"Low"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"N","value_label":"None"},{"metric":"I","name":"Integrity","value":"N","value_label":"None"},{"metric":"A","name":"Availability","value":"H","value_label":"High"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"ronf","vendor_name":"ronf","product_slug":"asyncssh","product_name":"asyncssh","version_start":"< 2.24.0","version_start_inclusive":true,"version_end":"< 2.24.0","version_end_inclusive":true,"cpe23_uri":"cve5:ronf:asyncssh:< 2.24.0:< 2.24.0"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/ronf/asyncssh/security/advisories/GHSA-rw4j-r22c-9gc3","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"https://github.com/ronf/asyncssh/commit/756cbae5350789ce9735f15f704bae9b5a3608b8","source_type":"PATCH","tags":["patch"]},{"url":"https://github.com/ronf/asyncssh/commit/9c354270c009285525e126721e8ed5fbed1f8a67","source_type":"PATCH","tags":["patch"]},{"url":"https://github.com/ronf/asyncssh/releases/tag/v2.24.0","source_type":"PATCH","tags":["patch"]}],"timeline":[{"type":"published","at":"2026-09-16T20:00:46.657000Z","label":"CVE published","source":null}]}