{"id":"CVE-2026-54590","state":"PUBLISHED","title":"AsyncSSH AuthorizedKeysFile username substitution bypass through ~ and environment expansion","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. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig._set_tokens that blocks /, , and .. before %u substitution in AuthorizedKeysFile but does not block a leading ~ or ${ENV}, allowing later expansion in _expand_val and Path(filename).expanduser() to escape the intended authorized-keys directory. This issue is fixed in version 2.23.1.","publishedAt":"2026-07-08T20:36:45.258Z","updatedAt":"2026-07-10T15:00:21.849Z","severity":{"score":5.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["ronf asyncssh"],"affected":[{"vendor":"ronf","product":"asyncssh","versions":[{"version":"< 2.23.1","status":"affected"}]}],"references":["https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh","https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88","https://github.com/ronf/asyncssh/releases/tag/v2.23.1"],"weaknesses":["CWE-22","CWE-639"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/54xxx/CVE-2026-54590.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-54590","state":"PUBLISHED","datePublished":"2026-07-08T20:36:45.258Z","dateUpdated":"2026-07-10T15:00:21.849Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-15T19:45:23.538Z"},"containers":{"cna":{"title":"AsyncSSH AuthorizedKeysFile username substitution bypass through ~ and environment expansion","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. Version 2.23.0 contains an incomplete fix for CVE-2026-45309 in SSHServerConfig._set_tokens that blocks /, , and .. before %u substitution in AuthorizedKeysFile but does not block a leading ~ or ${ENV}, allowing later expansion in _expand_val and Path(filename).expanduser() to escape the intended authorized-keys directory. This issue is fixed in version 2.23.1."}],"affected":[{"vendor":"ronf","product":"asyncssh","versions":[{"version":"< 2.23.1","status":"affected"}]}],"references":[{"url":"https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh","name":"https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88","name":"https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88","tags":["x_refsource_MISC"]},{"url":"https://github.com/ronf/asyncssh/releases/tag/v2.23.1","name":"https://github.com/ronf/asyncssh/releases/tag/v2.23.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-22","lang":"en","description":"CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-639","lang":"en","description":"CWE-639: Authorization Bypass Through User-Controlled Key","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-08T20:36:45.258Z"},"source":{"advisory":"GHSA-qr67-gv47-xwwh","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/ronf/asyncssh/security/advisories/GHSA-qr67-gv47-xwwh","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-10T15:00:13.292812Z","id":"CVE-2026-54590","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-10T15:00:21.849Z"}}]}}}