Out-of-bounds Read Affecting libssh2 package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.25% (17th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-CENTOS7-LIBSSH2-18324289
  • published27 Jul 2026
  • disclosed24 Jul 2026

Introduced: 24 Jul 2026

NewCVE-2026-66034  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

There is no fixed version for Centos:7 libssh2.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libssh2 package and not the libssh2 package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.

CVSS Base Scores

version 3.1