Packages
- libssh2 - Client-side C library implementing the SSH2 protocol
Details
It was discovered that libssh2 incorrectly handled the sftp_symlink()
function. A malicious SSH server or machine-in-the-middle attacker could
possibly use this issue to obtain sensitive information or cause a denial
of service. (CVE-2025-15661)
It was discovered that libssh2 had a pre-authentication denial of service
vulnerability in the SSH_MSG_EXT_INFO handler. A malicious SSH server could
possibly use this issue to cause a client CPU exhaustion loop, resulting in
a denial of service. (CVE-2026-55199)
It was discovered that libssh2 incorrectly handled packet length fields. A
remote attacker could possibly use this issue to execute arbitrary code.
This issue only affected Ubuntu 25.10 and Ubuntu 26.04 LTS.
(CVE-2026-55200)
It was discovered that libssh2 incorrectly handled the sftp_symlink()
function. A malicious SSH server or machine-in-the-middle attacker could
possibly use this issue to obtain sensitive information or cause a denial
of service. (CVE-2025-15661)
It was discovered that libssh2 had a pre-authentication denial of service
vulnerability in the SSH_MSG_EXT_INFO handler. A malicious SSH server could
possibly use this issue to cause a client CPU exhaustion loop, resulting in
a denial of service. (CVE-2026-55199)
It was discovered that libssh2 incorrectly handled packet length fields. A
remote attacker could possibly use this issue to execute arbitrary code.
This issue only affected Ubuntu 25.10 and Ubuntu 26.04 LTS.
(CVE-2026-55200)
Update instructions
In general, a standard system update will make all the necessary changes.
Learn more about how to get the fixes.The problem can be corrected by updating your system to the following package versions:
| Ubuntu Release | Package Version | ||
|---|---|---|---|
| 26.04 LTS resolute | libssh2-1t64 – 1.11.1-1ubuntu0.26.04.2 | ||
| 25.10 questing | libssh2-1t64 – 1.11.1-1ubuntu0.25.10.2 | ||
| 24.04 LTS noble | libssh2-1t64 – 1.11.0-4.1ubuntu0.24.04.2 | ||
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