CVE-2026-66032 | libssh2 through 1.11.1, fixed in commit 5e47761, contains a … | CVSS 8.8 HIGH

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.

Metadata

CVE ID: CVE-2026-66032
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-07-23 20:45 UTC
Published: 2026-07-24 16:32 UTC
Last updated: 2026-07-24 17:08 UTC
Primary CWE: CWE-415
Double Free
Vendor / Product: libssh2 / libssh2
Sources: cve.org · NVD

Severity & Metrics

8.8 HIGH CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: none
Automatable: no
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
libssh2	libssh2	—	0 ≤ 1.11.1, 5e4776146552d898b9c0e1b313cd093fa8dc92d0

Weakness (CWE)

CWE	Source	Description
CWE-415	cna	Double Free

CVSS scores (2)

Score	Severity	Version	Source	Vector
8.8	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.7	HIGH	4.0	cna	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

References (3)