Loop with Unreachable Exit Condition ('Infinite Loop') Affecting libssh2 package, versions <1.11.1-r7


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.92% (60th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-LIBSSH2-17973030
  • published15 Jul 2026
  • disclosed17 Jun 2026

Introduced: 17 Jun 2026

CVE-2026-55199  (opens in a new tab)
CWE-835  (opens in a new tab)

How to fix?

Upgrade Chainguard libssh2 to version 1.11.1-r7 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 Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.

CVSS Base Scores

version 3.1