{"id":"CVE-2026-48798","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-48798","summary":"SSH.NET: ScpClient Recursive Download Allows Arbitrary File Write via Server-Controlled SCP Filenames","details":"## Summary\n\n`ScpClient.Download(string directoryName, DirectoryInfo directoryInfo)` writes files and directories using names returned by the remote SCP server during recursive downloads, with no validation that the resulting path stays inside the requested local directory. A malicious, compromised, or man-in-the-middle SCP server can return names containing `../` sequences (or absolute paths), causing the client to create directories and write/overwrite files anywhere the client process has access. This is similar to OpenSSH [CVE-2019-6111](https://github.com/advisories/GHSA-jr78-hfw4-xp7g), but with directory traversal capability.\n\n## Impact\n\nA malicious/compromised/MITM SCP server can create or write files outside the intended download directory, anywhere the client process can write. Overwriting files such as ~/.ssh/authorized_keys, shell rc files, cron entries, or application binaries/config can lead to persistence, privilege escalation, or remote code execution on the client host. Requires the victim to perform a directory download from the attacker-controlled server.\n\n## Remediation\n\nThe fixed release ensures that remotely-supplied file and directory names are valid local names such that the constructed local path is contained within the given local directory, and throws `ScpException` when an invalid name is detected.\n\n[600be0de543765995a189b5d7cd4efac5007f3ce](https://github.com/sshnet/SSH.NET/commit/600be0de543765995a189b5d7cd4efac5007f3ce)","published":"2026-08-12T15:19:10Z","modified":"2026-08-12T15:30:08.953485357Z","cvss":{"score":7.1,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"NuGet","name":"SSH.NET","fixedVersion":"2026.0.0"}],"fix":{"url":"https://github.com/sshnet/SSH.NET/commit/600be0de543765995a189b5d7cd4efac5007f3ce","label":"sshnet/SSH.NET@600be0d"},"references":[{"type":"WEB","url":"https://github.com/sshnet/SSH.NET/security/advisories/GHSA-q939-rpr3-3284"},{"type":"WEB","url":"https://github.com/sshnet/SSH.NET/commit/600be0de543765995a189b5d7cd4efac5007f3ce"},{"type":"PACKAGE","url":"https://github.com/sshnet/SSH.NET"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T15:30:08.953485357Z"}}