CVE-2026-66032
libssh2 Double-Free Heap Corruption via sftp_open()
- State
- Published
- Severity
- 8.7 High
- Published
- Jul 24, 2026
- Updated
- Jul 28, 2026
- Reserved
- Jul 23, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 8.8 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H | VulnCheck |
Weaknesses
- CWE-415 Double Free
Affected Products
| Product | Versions |
|---|---|
libssh2libssh2 |
|
References
- Pull Requestissue-trackingpatch
- Patch Commitpatch
- https://www.vulncheck.com/advisories/libssh2-double-free-heap-corruption-via-sftp-openthird-party-advisory
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