{"id":"UBUNTU-CVE-2025-15661","details":"libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.","modified":"2026-09-22T15:30:12.192798707Z","published":"2026-06-18T21:16:00Z","related":["USN-8486-1"],"upstream":["CVE-2025-15661"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2025-15661"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2025-15661"},{"type":"REPORT","url":"https://github.com/libssh2/libssh2/pull/1705"},{"type":"REPORT","url":"https://github.com/libssh2/libssh2/pull/1717"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8486-1"}],"affected":[{"package":{"name":"libssh2","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.3-1","1.4.3-2","1.4.3-2ubuntu0.1","1.4.3-2ubuntu0.2","1.4.3-2ubuntu0.2+esm1","1.4.3-2ubuntu0.2+esm2","1.4.3-2ubuntu0.2+esm3","1.4.3-2ubuntu0.2+esm4"],"ecosystem_specific":{"binaries":[{"binary_name":"libssh2-1","binary_version":"1.4.3-2ubuntu0.2+esm4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}},{"package":{"name":"libssh2","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=esm-apps-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.5.0-2","1.5.0-2ubuntu0.1","1.5.0-2ubuntu0.1+esm1","1.5.0-2ubuntu0.1+esm2","1.5.0-2ubuntu0.1+esm3"],"ecosystem_specific":{"binaries":[{"binary_name":"libssh2-1","binary_version":"1.5.0-2ubuntu0.1+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}},{"package":{"name":"libssh2","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.8.0-1","1.8.0-1ubuntu0.1","1.8.0-1ubuntu0.1+esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"libssh2-1","binary_version":"1.8.0-1ubuntu0.1+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}},{"package":{"name":"libssh2","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.8.0-2.1build1","1.8.0-2.1ubuntu0.1","1.8.0-2.1ubuntu0.1+esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.8.0-2.1ubuntu0.1+esm1","binary_name":"libssh2-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}},{"package":{"name":"libssh2","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.9.0-3","1.10.0-2","1.10.0-2build1","1.10.0-3","1.10.0-3ubuntu0.1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.10.0-3ubuntu0.1","binary_name":"libssh2-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}},{"package":{"name":"libssh2","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.11.0-4.1ubuntu0.24.04.2"}]}],"versions":["1.11.0-2","1.11.0-3","1.11.0-4","1.11.0-4.1build1","1.11.0-4.1build2","1.11.0-4.1ubuntu0.24.04.1"],"ecosystem_specific":{"binaries":[{"binary_name":"libssh2-1t64","binary_version":"1.11.0-4.1ubuntu0.24.04.2"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}},{"package":{"name":"libssh2","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.11.1-1ubuntu0.25.10.2"}]}],"versions":["1.11.1-1","1.11.1-1build1","1.11.1-1ubuntu0.25.10.1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"1.11.1-1ubuntu0.25.10.2","binary_name":"libssh2-1t64"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}},{"package":{"name":"libssh2","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/libssh2?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.11.1-1ubuntu0.26.04.2"}]}],"versions":["1.11.1-1build1","1.11.1-1build2","1.11.1-1ubuntu0.26.04.1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_version":"1.11.1-1ubuntu0.26.04.2","binary_name":"libssh2-1t64"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-15661.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}