CVE-2026-55200 | libssh2 through 1.11.1, fixed in commit 7acf3df contains an … | CVSS 8.1 HIGH

Description

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

Metadata

CVE ID: CVE-2026-55200
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-06-16 15:53 UTC
Published: 2026-06-17 19:03 UTC
Last updated: 2026-06-17 19:45 UTC
Primary CWE: CWE-680
Integer Overflow to Buffer Overflow
Vendor / Product: libssh2 / libssh2
Sources: cve.org · NVD

Severity & Metrics

8.1 HIGH CVSS 3.1

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC — CISA Coordinator

Exploitation: none
Automatable: no
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
libssh2	libssh2	—	0 ≤ 1.11.1, 7acf3dfda80c91c3a8c9f2372546301d4a1a7a8

Weakness (CWE)

CWE	Source	Description
CWE-680	cna	Integer Overflow to Buffer Overflow

CVSS scores (2)

Score	Severity	Version	Source	Vector
9.2	CRITICAL	4.0	cna	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
8.1	HIGH	3.1	cna	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References (3)