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CVE-2026-66034

HIGH
7.5
CVSS 3.1
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.

Metadata

CVE ID
CVE-2026-66034
State
PUBLISHED
Assigner
VulnCheck
Reserved
2026-07-23 20:45 UTC
Published
2026-07-24 16:42 UTC
Last updated
2026-07-24 17:31 UTC
Primary CWE
CWE-125
Out-of-bounds Read
Vendor / Product
libssh2 / libssh2
Sources
cve.org  ·  NVD

Severity & Metrics

7.5 HIGH CVSS 3.1
CVSS:3.1/AV:N/AC:H/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)
VendorProductPlatformVersions
libssh2 libssh2 — 0 ≤ 1.11.1, a13bb6c773f0d55ad1628cede57e99803cd898d9
Weakness (CWE)
CWESourceDescription
CWE-125 cna Out-of-bounds Read
CWE-908 cna Use of Uninitialized Resource
CVSS scores (2)
ScoreSeverityVersionSourceVector
7.7 HIGH 4.0 cna 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
7.5 HIGH 3.1 cna CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
References (3)
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