CVE-2026-66032 Affecting libssh2 package, versions <0:1.4.3-12.amzn2.2.9


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.45% (38th percentile)

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  • Snyk IDSNYK-AMZN2-LIBSSH2-18904594
  • published18 Aug 2026
  • disclosed24 Jul 2026

Introduced: 24 Jul 2026

CVE-2026-66032  (opens in a new tab)
CWE-1341  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2 libssh2 to version 0:1.4.3-12.amzn2.2.9 or higher.
This issue was patched in ALAS2-2026-3861.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libssh2 package and not the libssh2 package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1