ProFTPD Project vulnerabilities and threats

ProFTPD through 1.3.9e and 1.3.10rc1 through 1.3.10rc4 contains a link-following vulnerability in mod_copy that allows authenticated FTP users to bypass Limit WRITE restrictions via symlinks. Attackers can place a symlink in a writable directory and use SITE COPY or SITE CPTO to overwrite files in write-denied locations.

CVE-2026-119147 is an authorization bypass vulnerability in ProFTPD versions before 1.3.9e and 1.3.10rc5. It affects the mod_sftp copy-file extension handler, allowing authenticated SFTP users to copy readable files to new locations in directories where write permissions are denied. This bypasses the intended Limit WRITE restrictions, enabling unauthorized file creation in protected directories.

ProFTPD versions before 1.3.9e and between 1.3.10rc1 and before 1.3.10rc5 contain a buffer overflow vulnerability in the mod_rewrite int:utf8trans RewriteMap. This flaw allows remote attackers to send FTP command arguments longer than 1024 bytes, potentially overwriting static buffers and corrupting session memory, which can lead to session crashes. The vulnerability can be exploited without authentication if pre-login commands are rewritten.

ProFTPD mod_sftp contains a heap-based buffer overflow reachable by an authenticated SFTP user. The fxp_packet_read() function accepts the attacker-supplied 32-bit big-endian SFTP packet length without a minimum sanity check. A value of 0 causes an unsigned subtraction elsewhere in the read path to underflow to approximately 4 GB. That oversized request reaches the core memory allocator, where the rounded size is computed in size_t but passed to new_block() as a 32-bit int; the low 32 bits of 0x100000000 are 0, so new_block() returns a small (~512-byte) block while the caller is told it received ~4 GB. The subsequent fill loop then streams attacker-controlled bytes past the end of the 544-byte allocation, producing an attacker-controlled heap buffer overflow. An authenticated user can crash the per-connection ProFTPD session child on demand with a single malformed SFTP packet (packet_len=0 followed by a body greater than approximately 544 bytes), producing reliable authenticated remote denial of service. Depending on heap layout and adjacent allocations, heap metadata corruption and further consequences beyond denial of service may be possible, though only denial of service is demonstrated by the supplied proof of concept.

ProFTPD through 1.3.9b and 1.3.10rc2 contains an access control bypass vulnerability that allows authenticated FTP users to circumvent Directory ACL restrictions by prefixing paths with /proc/self/root in the RNFR command handler. Attackers can exploit the unresolved symlink components in dir_canonical_path() to cause dir_check() to perform lexical path comparisons that match no configured Directory block, enabling rename operations on files in DenyAll-protected directories and subsequent retrieval of those files. Mitigation: Sessions configured with DefaultRoot (chroot) are not affected, as chroot changes the directory to which /proc/self/root resolves.