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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-66034 Detail

Description

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  VulnCheck
CVSS-B 7.7 HIGH
Vector:  CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/libssh2/libssh2/commit/a13bb6c773f0d55ad1628cede57e99803cd898d9 VulnCheck Patch 
https://github.com/libssh2/libssh2/pull/2202 VulnCheck Issue Tracking  Patch 
https://www.vulncheck.com/advisories/libssh2-heap-out-of-bounds-read-via-publickey-subsystem VulnCheck Patch  Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-125 Out-of-bounds Read VulnCheck  
CWE-908 Use of Uninitialized Resource VulnCheck  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

4 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-66034
NVD Published Date:
07/24/2026
NVD Last Modified:
07/30/2026
Source:
VulnCheck