CVE-2026-53994— ProFTPD 缓冲区错误漏洞

ProFTPD mod_sftp Heap Buffer Overflow via Unsigned Integer Underflow and Size Truncation

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.

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

堆缓冲区溢出

ProFTPD 缓冲区错误漏洞

ProFTPD是ProFTPD团队开源的一套可配置性强的开放源代码的FTP服务器软件。 ProFTPD 1.3.10之前版本存在缓冲区错误漏洞，该漏洞源于mod_sftp的fxp_packet_read()函数对攻击者提供的32位大端SFTP数据包长度未进行最小合理性检查，0值导致读取路径中的无符号减法下溢至约4GB，进而通过内存分配器中的大小截断问题触发堆缓冲区溢出，可能导致经过身份验证的用户通过单个畸形SFTP数据包造成拒绝服务。

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