ALPINE-CVE-2026-55199
libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.
ALPINE-CVE-2026-55199
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:ALPINE-CVE-2026-55199
libssh2
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.11.1-r2
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
libssh2
Source reference: /affected/1/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.11.1-r2
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
libssh2
Source reference: /affected/2/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.11.1-r3
Source reference:
/affected/2/ranges - Prerequisites
- Not stated in this record
libssh2
Source reference: /affected/3/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.11.1-r3
Source reference:
/affected/3/ranges - Prerequisites
- Not stated in this record
rust
Source reference: /affected/4/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.96.1-r0
Source reference:
/affected/4/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.11.1-r2"
}
]
}
],
"package": {
"name": "libssh2",
"purl": "pkg:apk/alpine/libssh2?arch=source",
"ecosystem": "Alpine:v3.21"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-55199.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.11.1-r2"
}
]
}
],
"package": {
"name": "libssh2",
"purl": "pkg:apk/alpine/libssh2?arch=source",
"ecosystem": "Alpine:v3.22"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-55199.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.11.1-r3"
}
]
}
],
"package": {
"name": "libssh2",
"purl": "pkg:apk/alpine/libssh2?arch=source",
"ecosystem": "Alpine:v3.23"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-55199.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.11.1-r3"
}
]
}
],
"package": {
"name": "libssh2",
"purl": "pkg:apk/alpine/libssh2?arch=source",
"ecosystem": "Alpine:v3.24"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-55199.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.96.1-r0"
}
]
}
],
"package": {
"name": "rust",
"purl": "pkg:apk/alpine/rust?arch=source",
"ecosystem": "Alpine:v3.24"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-55199.json"
},
"ecosystem_specific": {}
}
]Publisher severity
No explicit severity was provided.
- Event
- #54531 · Revision 1
- Added to Heist Feed
- Publisher date