CVE-2025-57632

libsmb2 6.2+ is vulnerable to Buffer Overflow. When processing SMB2 chained PDUs (NextCommand), libsmb2 repeatedly calls smb2_add_iovector() to append to a fixed-size iovec array without checking the upper bound of v->niov (SMB2_MAX_VECTORS=256). An attacker can craft responses with many chained PDUs to overflow v->niov and perform heap out-of-bounds writes, causing memory corruption, crashes, and potentially arbitrary code execution. The SMB2_OPLOCK_BREAK path bypasses message ID validation.

• https://gist.github.com/ZjW1nd/0b95b63307ceee7890e88e4abc6f041e
• https://github.com/sahlberg/libsmb2
• https://github.com/sahlberg/libsmb2/blob/master/lib/compat.c#L569
• https://github.com/sahlberg/libsmb2/commit/5e75eebf922b338cdb548d60cffb3b997d2a12e8