Medium
python-asyncssh — security advisory
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.
- Products
- python-asyncssh
- Affected versions
- 1.11.0-2, 1.11.1-1, 1.11.1-1ubuntu0.1~esm1, 1.11.1-1ubuntu0.1~esm2, 1.12.2-1, 1.12.2-1ubuntu0.1, 1.12.2-1ubuntu0.2, 1.2.0-1, 1.2.1-1, 1.3.0-1, 1.8.1-2, 2.10.1-2, 2.10.1-2ubuntu0.1, 2.10.1-2ubuntu0.1+esm1, 2.20.0-1, 2.21.1-1, 2.23.0-1, 2.5.0-1, 2.5.0-1ubuntu0.1, 2.5.0-1ubuntu0.1+esm1, 2.5.0-1ubuntu0.1~esm1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-54590
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:46 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-54590
python-asyncssh
Fixed versions: Not specified
python-asyncssh
Fixed versions: Not specified
python-asyncssh
Fixed versions: Not specified
python-asyncssh
Fixed versions: Not specified
python-asyncssh
Fixed versions: Not specified
python-asyncssh
Fixed versions: Not specified
python-asyncssh
Fixed versions: Not specified
python-asyncssh
Fixed versions: Not specified
Complete source record
{
"id": "8051d17ed0ed1814cff6c92330d87c99d3d4d24de30cb82347b6d0686f4d5838",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-54590",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-54590",
"summary": "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.",
"evidence": "osv:UBUNTU-CVE-2026-54590",
"products": [
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{
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{
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{
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"evidence": "/affected/6/versions"
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{
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},
{
"name": {
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"evidence": "/affected/7/package/name"
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"evidence": "/affected/7/versions"
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{
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"severity": "medium",
"structured": {
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"aliases": [
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],
"metrics": [
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"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"
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"ecosystem": "Ubuntu:16.04:LTS"
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"1.2.1-1",
"1.3.0-1"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
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"purl": "pkg:deb/ubuntu/python-asyncssh?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
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"1.11.0-2",
"1.11.1-1",
"1.11.1-1ubuntu0.1~esm1",
"1.11.1-1ubuntu0.1~esm2"
],
"database_specific": {
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},
"ecosystem_specific": {
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},
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"1.12.2-1ubuntu0.1",
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},
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],
"modified": "2026-10-17T12:59:07.014298428Z",
"provider": "osv",
"upstream": [
"CVE-2026-54590"
],
"references": [
"https://ubuntu.com/security/CVE-2026-54590",
"https://www.cve.org/CVERecord?id=CVE-2026-54590",
"https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88",
"https://github.com/ronf/asyncssh/releases/tag/v2.23.1",
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],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 359315,
"published_at": "2026-07-08T21:16:00+00:00"
}