{"id":"CVE-2026-45309","aliases":["DEBIAN-CVE-2026-45309","EUVD-2026-45255","GHSA-g794-3fmp-753h","PYSEC-2026-2384","UBUNTU-CVE-2026-45309","openSUSE-SU-2026:11042-1"],"status":"published","title":"AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username","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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.","severity":{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00592,"percentile":0.48579,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-22"],"published":"2026-05-27T21:35:06Z","modified":"2026-10-28T02:31:01Z","fixes":[{"ecosystem":"PyPI","package":"asyncssh","fixed_in":["2.23.0"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:14","package":"python-asyncssh","fixed_in":["2.23.0-1"],"sources":["osv"]},{"ecosystem":"openSUSE:Tumbleweed","package":"python-asyncssh","fixed_in":["2.23.1-1.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.22.0"},{"last_affected":"2.22.0"},{"fixed":"2.23.0"}]}],"versions":["2.22.0"]},{"source":"osv","ecosystem":"Debian:12","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.10.1-2","2.10.1-2+deb12u1","2.10.1-2+deb12u2","2.15.0-1","2.16.0-1","2.17.0-1","2.17.0-2","2.18.0-1","2.19.0-1","2.20.0-1","2.21.0-1","2.21.1-1","2.22.0-1","2.22.0-2","2.23.0-1","2.24.0-1","2.24.0-2"]},{"source":"osv","ecosystem":"Debian:13","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.20.0-1","2.21.0-1","2.21.1-1","2.22.0-1","2.22.0-2","2.23.0-1","2.24.0-1","2.24.0-2"]},{"source":"osv","ecosystem":"Debian:14","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.23.0-1"}]}],"versions":["2.20.0-1","2.21.0-1","2.21.1-1","2.22.0-1","2.22.0-2"]},{"source":"osv","ecosystem":"PyPI","package":"asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.22.0"},{"fixed":"2.23.0"}]}],"versions":["2.22.0"]},{"source":"osv","ecosystem":"PyPI","package":"asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.22.0"},{"fixed":"2.23.0"}]}],"versions":["2.22.0"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.0-1","1.2.1-1","1.3.0-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.8.1-2","1.11.0-2","1.11.1-1","1.11.1-1ubuntu0.1~esm1","1.11.1-1ubuntu0.1~esm2"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.12.2-1","1.12.2-1ubuntu0.1","1.12.2-1ubuntu0.2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.5.0-1","2.5.0-1ubuntu0.1~esm1","2.5.0-1ubuntu0.1","2.5.0-1ubuntu0.1+esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.10.1-2","2.10.1-2ubuntu0.1","2.10.1-2ubuntu0.1+esm1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.20.0-1","2.21.1-1"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"python-asyncssh","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.23.1-1.1"}]}]}],"products":[{"vendor":"asyncssh_project","product":"asyncssh"},{"vendor":"ronf","product":"asyncssh"}],"references":[{"url":"https://github.com/ronf/asyncssh/security/advisories/GHSA-g794-3fmp-753h","tags":["x_refsource_CONFIRM","exploit","Exploit","Vendor Advisory","advisory","web"]},{"url":"https://github.com/ronf/asyncssh/commit/2af2382cce946c959a378a62f257af253dc4ab51","tags":["x_refsource_MISC","Patch","fix"]},{"url":"https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88","tags":["x_refsource_MISC","Patch","fix"]},{"url":"https://github.com/advisories/GHSA-g794-3fmp-753h","tags":["advisory","report"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45309.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45309","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-45309","tags":["advisory"]},{"url":"https://github.com/ronf/asyncssh","tags":["package"]},{"url":"https://pypi.org/project/asyncssh","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-45309","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-45309","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2026-45309","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-45309","title":"AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username","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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.","status":"published","published":"2026-07-17T18:40:02.428Z","modified":"2026-07-21T01:55:16.704Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T13:46:55.086623Z"}],"euvd":[{"id":"EUVD-2026-45255","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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.","status":"published","published":"2026-07-17T18:40:02Z","modified":"2026-07-21T01:55:16Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T18:19:47.959089Z"}],"ghsa":[{"id":"GHSA-g794-3fmp-753h","title":"AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username","description":"## Summary\nAsyncSSH 2.22.0 expands the OpenSSH-compatible `AuthorizedKeysFile` `%u` token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as `AuthorizedKeysFile authorized_keys/%u` can be made to read an authorized-keys file outside the intended directory when the SSH username contains path traversal segments. If the attacker can place or reference a readable authorized-keys-format file containing their public key, the attacker can authenticate over SSH as the traversal username.\n\n## Affected Product\n- Package: asyncssh\n- Ecosystem: pip\n- Affected versions: confirmed on 2.22.0; exact lower bound not finalized\n- Tested version: 2.22.0\n- Audit commit/tag: tag `v2.22.0`, commit `af5a81e669633d83d535163f93b6bf3f957c9238`\n- PyPI sdist SHA256: `c3ce72b01be4f97b40e62844dd384227e5ff5a401a3793007c42f86a5c8eb537`\n\n## Vulnerability Details\n- CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory\n- Component: AsyncSSH server config reload and public-key authentication (`asyncssh/config.py`, `asyncssh/connection.py`, `asyncssh/auth_keys.py`, `asyncssh/misc.py`)\n- Root cause: `%u` in `AuthorizedKeysFile` is expanded from the remote username without rejecting path separators or `..` segments, and the resulting path is opened without constraining it to the intended authorized-keys directory.\n- Security boundary violated: the configured authorized-keys directory and public-key authentication trust boundary.\n- Direct impact: public-key authentication succeeds using an attacker-selected authorized-keys file outside the intended directory.\n- Chain impact, if any: none claimed; direct authentication impact is primary.\n\n## Attack Preconditions\n- The AsyncSSH server uses a config or equivalent pattern where `AuthorizedKeysFile` contains `%u`, for example `AuthorizedKeysFile authorized_keys/%u`.\n- Public-key authentication is enabled.\n- The attacker can place or reference a readable authorized-keys-format file outside the intended directory, such as a file in a world-writable or application-writable location.\n- The application does not separately reject usernames containing `/`, `\\`, or `..` before AsyncSSH uses the username for key-file selection.\n\n## Reproduction\nThe run-scoped evidence contains a safe localhost proof:\n\n1. Start the proof harness saved at \n[harness_app.py](https://github.com/user-attachments/files/27232526/harness_app.py)\n\n2. Run \n[exploit_proof.py](https://github.com/user-attachments/files/27232538/exploit_proof.py)\nthrough \n[run_proof.sh](https://github.com/user-attachments/files/27232545/run_proof.sh)\n\n3. The harness creates `sshd_config` with `AuthorizedKeysFile authorized_keys/%u`, writes the attacker's public key to a file outside `authorized_keys/`, starts a real AsyncSSH server, and attempts two SSH logins.\n4. Expected result: the normal username `victim` fails, while the traversal username authenticates with the same attacker key.\n\nObserved proof output:\n\n```text\n[CONTROL] username=victim success=False\n[ATTACK] username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub success=True\n[ATTACK] output=AUTH_BYPASS_SUCCESS username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub\nPASS: traversal username authenticated with attacker-controlled authorized_keys file\n```","status":"published","published":"2026-05-27T21:35:06Z","modified":"2026-05-27T21:35:07Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T14:40:14.666177Z"}],"nvd":[{"id":"CVE-2026-45309","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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.","status":"published","published":"2026-07-17T19:17:14.333Z","modified":"2026-10-24T20:10:00.137Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high","assessor":"primary"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T14:12:30.250437Z"}],"osv":[{"id":"CVE-2026-45309","title":"AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username","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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.","status":"published","published":"2026-07-17T18:40:02.428Z","modified":"2026-10-28T02:31:01.695218938Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T15:45:05.172514Z"},{"id":"DEBIAN-CVE-2026-45309","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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.","status":"published","published":"2026-07-17T19:17:14.333Z","modified":"2026-10-25T09:47:29.676628761Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:45:55.669088Z"},{"id":"GHSA-g794-3fmp-753h","title":"AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username","description":"## Summary\nAsyncSSH 2.22.0 expands the OpenSSH-compatible `AuthorizedKeysFile` `%u` token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as `AuthorizedKeysFile authorized_keys/%u` can be made to read an authorized-keys file outside the intended directory when the SSH username contains path traversal segments. If the attacker can place or reference a readable authorized-keys-format file containing their public key, the attacker can authenticate over SSH as the traversal username.\n\n## Affected Product\n- Package: asyncssh\n- Ecosystem: pip\n- Affected versions: confirmed on 2.22.0; exact lower bound not finalized\n- Tested version: 2.22.0\n- Audit commit/tag: tag `v2.22.0`, commit `af5a81e669633d83d535163f93b6bf3f957c9238`\n- PyPI sdist SHA256: `c3ce72b01be4f97b40e62844dd384227e5ff5a401a3793007c42f86a5c8eb537`\n\n## Vulnerability Details\n- CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory\n- Component: AsyncSSH server config reload and public-key authentication (`asyncssh/config.py`, `asyncssh/connection.py`, `asyncssh/auth_keys.py`, `asyncssh/misc.py`)\n- Root cause: `%u` in `AuthorizedKeysFile` is expanded from the remote username without rejecting path separators or `..` segments, and the resulting path is opened without constraining it to the intended authorized-keys directory.\n- Security boundary violated: the configured authorized-keys directory and public-key authentication trust boundary.\n- Direct impact: public-key authentication succeeds using an attacker-selected authorized-keys file outside the intended directory.\n- Chain impact, if any: none claimed; direct authentication impact is primary.\n\n## Attack Preconditions\n- The AsyncSSH server uses a config or equivalent pattern where `AuthorizedKeysFile` contains `%u`, for example `AuthorizedKeysFile authorized_keys/%u`.\n- Public-key authentication is enabled.\n- The attacker can place or reference a readable authorized-keys-format file outside the intended directory, such as a file in a world-writable or application-writable location.\n- The application does not separately reject usernames containing `/`, `\\`, or `..` before AsyncSSH uses the username for key-file selection.\n\n## Reproduction\nThe run-scoped evidence contains a safe localhost proof:\n\n1. Start the proof harness saved at \n[harness_app.py](https://github.com/user-attachments/files/27232526/harness_app.py)\n\n2. Run \n[exploit_proof.py](https://github.com/user-attachments/files/27232538/exploit_proof.py)\nthrough \n[run_proof.sh](https://github.com/user-attachments/files/27232545/run_proof.sh)\n\n3. The harness creates `sshd_config` with `AuthorizedKeysFile authorized_keys/%u`, writes the attacker's public key to a file outside `authorized_keys/`, starts a real AsyncSSH server, and attempts two SSH logins.\n4. Expected result: the normal username `victim` fails, while the traversal username authenticates with the same attacker key.\n\nObserved proof output:\n\n```text\n[CONTROL] username=victim success=False\n[ATTACK] username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub success=True\n[ATTACK] output=AUTH_BYPASS_SUCCESS username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub\nPASS: traversal username authenticated with attacker-controlled authorized_keys file\n```","status":"published","published":"2026-05-27T21:35:06Z","modified":"2026-09-10T03:50:47.025000862Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium"}],"cwes":["CWE-22"],"updated_at":"2026-11-02T15:46:47.472172Z"},{"id":"PYSEC-2026-2384","title":"AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username","description":"## Summary\nAsyncSSH 2.22.0 expands the OpenSSH-compatible `AuthorizedKeysFile` `%u` token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as `AuthorizedKeysFile authorized_keys/%u` can be made to read an authorized-keys file outside the intended directory when the SSH username contains path traversal segments. If the attacker can place or reference a readable authorized-keys-format file containing their public key, the attacker can authenticate over SSH as the traversal username.\n\n## Affected Product\n- Package: asyncssh\n- Ecosystem: pip\n- Affected versions: confirmed on 2.22.0; exact lower bound not finalized\n- Tested version: 2.22.0\n- Audit commit/tag: tag `v2.22.0`, commit `af5a81e669633d83d535163f93b6bf3f957c9238`\n- PyPI sdist SHA256: `c3ce72b01be4f97b40e62844dd384227e5ff5a401a3793007c42f86a5c8eb537`\n\n## Vulnerability Details\n- CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory\n- Component: AsyncSSH server config reload and public-key authentication (`asyncssh/config.py`, `asyncssh/connection.py`, `asyncssh/auth_keys.py`, `asyncssh/misc.py`)\n- Root cause: `%u` in `AuthorizedKeysFile` is expanded from the remote username without rejecting path separators or `..` segments, and the resulting path is opened without constraining it to the intended authorized-keys directory.\n- Security boundary violated: the configured authorized-keys directory and public-key authentication trust boundary.\n- Direct impact: public-key authentication succeeds using an attacker-selected authorized-keys file outside the intended directory.\n- Chain impact, if any: none claimed; direct authentication impact is primary.\n\n## Attack Preconditions\n- The AsyncSSH server uses a config or equivalent pattern where `AuthorizedKeysFile` contains `%u`, for example `AuthorizedKeysFile authorized_keys/%u`.\n- Public-key authentication is enabled.\n- The attacker can place or reference a readable authorized-keys-format file outside the intended directory, such as a file in a world-writable or application-writable location.\n- The application does not separately reject usernames containing `/`, `\\`, or `..` before AsyncSSH uses the username for key-file selection.\n\n## Reproduction\nThe run-scoped evidence contains a safe localhost proof:\n\n1. Start the proof harness saved at \n[harness_app.py](https://github.com/user-attachments/files/27232526/harness_app.py)\n\n2. Run \n[exploit_proof.py](https://github.com/user-attachments/files/27232538/exploit_proof.py)\nthrough \n[run_proof.sh](https://github.com/user-attachments/files/27232545/run_proof.sh)\n\n3. The harness creates `sshd_config` with `AuthorizedKeysFile authorized_keys/%u`, writes the attacker's public key to a file outside `authorized_keys/`, starts a real AsyncSSH server, and attempts two SSH logins.\n4. Expected result: the normal username `victim` fails, while the traversal username authenticates with the same attacker key.\n\nObserved proof output:\n\n```text\n[CONTROL] username=victim success=False\n[ATTACK] username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub success=True\n[ATTACK] output=AUTH_BYPASS_SUCCESS username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub\nPASS: traversal username authenticated with attacker-controlled authorized_keys file\n```","status":"published","published":"2026-07-13T15:19:12.785321Z","modified":"2026-07-13T16:31:31.297854793Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","level":"medium"}],"updated_at":"2026-11-02T15:52:55.961245Z"},{"id":"UBUNTU-CVE-2026-45309","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 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.","status":"published","published":"2026-07-17T19:17:00Z","modified":"2026-08-04T11:00:09.516775131Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","level":"high"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T16:56:26.396868Z"},{"id":"openSUSE-SU-2026:11042-1","title":"python311-asyncssh-2.23.1-1.1 on GA media","description":"These are all security issues fixed in the python311-asyncssh-2.23.1-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-06-16T00:00:00Z","modified":"2026-06-17T09:15:08.01585241Z","updated_at":"2026-11-02T16:58:38.95195Z"}]}}