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CVE-2026-55200— libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c

CVSS 8.1 · High EPSS 0.55% · P42

Affected Version Matrix 2

VendorProductVersion RangeStatus
libssh2libssh2≤ 1.11.1affected
7acf3dfda80c91c3a8c9f2372546301d4a1a7a8unaffected
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I. Basic Information for CVE-2026-55200

Vulnerability Information
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Vulnerability Title
libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c
Source: NVD (National Vulnerability Database)
Vulnerability 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.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
整数溢出导致缓冲区溢出
Source: NVD (National Vulnerability Database)
Vulnerability Title
libssh2 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
libssh2是libssh2团队开源的一款实现SSH2协议的客户端C库。 libssh2 1.11.1及之前版本存在数字错误漏洞，该漏洞源于ssh2_transport_read()函数未对packet_length字段进行上限检查，可能导致越界写入，远程攻击者可发送特制的过大数据包长度的SSH数据包破坏堆内存并实现远程代码执行。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
libssh2libssh2 0 ~ 1.11.1 -

II. Public POCs for CVE-2026-55200

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III. Intelligence Information for CVE-2026-55200

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Patches & Fixes for CVE-2026-55200 (2)

Vendor Advisories for CVE-2026-55200 (1)

IV. Related Vulnerabilities

Same product: libssh2
Same vendor: libssh2
Same weakness: CWE-680

V. Comments for CVE-2026-55200

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