CVE-2026-66032
libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.
- Score
- CVSS 3.1 8.8 High
- Status
- Analyzed - disclosure@vulncheck.com
- Published
- 2026-07-24
- Last modified
- 2026-07-28
- Weaknesses
- CWE-415
Affected products
References
- https://github.com/libssh2/libssh2/commit/5e4776146552d898b9c0e1b313cd093fa8dc92d0
- https://github.com/libssh2/libssh2/pull/2180
- https://www.vulncheck.com/advisories/libssh2-double-free-heap-corruption-via-sftp-open
