Out-of-bounds Read Affecting libssh2 package, versions <1.10.0-3+deb12u1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.4% (34th percentile)

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  • Snyk IDSNYK-ECHOLATEST-LIBSSH2-18306963
  • published25 Jul 2026
  • disclosed24 Jul 2026

Introduced: 24 Jul 2026

CVE-2026-66034  (opens in a new tab)
CWE-125  (opens in a new tab)
CWE-908  (opens in a new tab)

How to fix?

Upgrade Echo:latest libssh2 to version 1.10.0-3+deb12u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libssh2 package and not the libssh2 package as distributed by Echo. See How to fix? for Echo:latest 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