MediumFix available
libssh — security advisory
A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.
- Products
- libssh
- Affected versions
- 0.10.5-2, 0.10.5-3, 0.10.5-3+hurd.1, 0.10.6-0+deb12u1, 0.10.6-0+deb12u2, 0.11.2-1, 0.11.2-1+deb13u1, 0.11.3-1, 0.12.0-1, 0.12.0-2, 0.12.0-3, 0.12.1-1
- Fixed versions
- 0.10.6-0+deb12u3, 0.11.5-0+deb13u1, 0.12.2-1
- CVEs
- CVE-2026-59843
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 13:26 UTC · Revision 1
Source evidence
A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.
osv:DEBIAN-CVE-2026-59843
libssh
Fixed versions: 0.10.6-0+deb12u3
libssh
Fixed versions: 0.11.5-0+deb13u1
libssh
Fixed versions: 0.12.2-1
Complete source record
{
"id": "e0fe8a81aada7fc06d31bc2f6b15e012594d84651c247933f1662111fba43268",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-59843",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-59843",
"summary": "A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.",
"evidence": "osv:DEBIAN-CVE-2026-59843",
"products": [
{
"name": {
"value": "libssh",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.10.6-0+deb12u3",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "0.10.5-2",
"evidence": "/affected/0/versions"
},
{
"value": "0.10.5-3",
"evidence": "/affected/0/versions"
},
{
"value": "0.10.5-3+hurd.1",
"evidence": "/affected/0/versions"
},
{
"value": "0.10.6-0+deb12u1",
"evidence": "/affected/0/versions"
},
{
"value": "0.10.6-0+deb12u2",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "libssh",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.11.5-0+deb13u1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": [
{
"value": "0.11.2-1",
"evidence": "/affected/1/versions"
},
{
"value": "0.11.2-1+deb13u1",
"evidence": "/affected/1/versions"
},
{
"value": "0.11.3-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "libssh",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.12.2-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "0.11.2-1",
"evidence": "/affected/2/versions"
},
{
"value": "0.11.3-1",
"evidence": "/affected/2/versions"
},
{
"value": "0.12.0-1",
"evidence": "/affected/2/versions"
},
{
"value": "0.12.0-2",
"evidence": "/affected/2/versions"
},
{
"value": "0.12.0-3",
"evidence": "/affected/2/versions"
},
{
"value": "0.12.1-1",
"evidence": "/affected/2/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2026-59843",
"aliases": [
"DEBIAN-CVE-2026-59843"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.10.6-0+deb12u3"
}
]
}
],
"package": {
"name": "libssh",
"purl": "pkg:deb/debian/libssh?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"0.10.5-2",
"0.10.5-3",
"0.10.5-3+hurd.1",
"0.10.6-0+deb12u1",
"0.10.6-0+deb12u2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-59843.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.11.5-0+deb13u1"
}
]
}
],
"package": {
"name": "libssh",
"purl": "pkg:deb/debian/libssh?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"0.11.2-1",
"0.11.2-1+deb13u1",
"0.11.3-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-59843.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.12.2-1"
}
]
}
],
"package": {
"name": "libssh",
"purl": "pkg:deb/debian/libssh?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"0.11.2-1",
"0.11.3-1",
"0.12.0-1",
"0.12.0-2",
"0.12.0-3",
"0.12.1-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-59843.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-20T21:00:07.078534759Z",
"provider": "osv",
"upstream": [
"CVE-2026-59843"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-59843"
]
},
"related_cves": [
{
"value": "CVE-2026-59843",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 390703,
"published_at": "2026-07-21T12:18:57.86+00:00"
}