libssh2 vulnerabilities
Summary
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) Affected Ubuntu releases: 26.04, 25.10, 24.04. CVEs: CVE-2026-55200, CVE-2026-55199, CVE-2025-15661.
- Ubuntu 26.04
- Ubuntu 25.10
- Ubuntu 24.04
Official advisory · medium-confidence parse· fetched 3 hours ago·verify at source
Mitigation checklist
- Apply available updates: `sudo apt update && sudo apt upgrade` (a standard system update installs the fix).
Official advisory · medium-confidence parse· fetched 3 hours ago·verify at source
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