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CVE-2021-3634

Quick assessment

Affected
n/a libssh
Exploitation
High exploitation probability; assess promptly
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Libssh是Libssh组织的一个用于访问SSH服务的C语言开发包，它能够执行远程命令、文件传输，同时为远程的程序提供安全的传输通道。 libssh 存在缓冲区错误漏洞，该漏洞源于 libssh 允许在密钥重新交换操作中改变密钥交换方法。改变密钥交换方法时，如果采用不同长度的 hash ，将会导致缓冲区错误。

AI Predicted 7.5 Difficulty: Hard EPSS 4.68% · P92

Possible ATT&CK Techniques 1 AI

T1557 · Adversary-in-the-Middle
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I. Basic Information for CVE-2021-3634

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating "secret_hash" of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5
Vulnerability Title
Libssh 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Libssh是Libssh组织的一个用于访问SSH服务的C语言开发包，它能够执行远程命令、文件传输，同时为远程的程序提供安全的传输通道。 libssh 存在缓冲区错误漏洞，该漏洞源于 libssh 允许在密钥重新交换操作中改变密钥交换方法。改变密钥交换方法时，如果采用不同长度的 hash ，将会导致缓冲区错误。
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

Vendor Product Affected Versions CPE Subscribe
- libssh libssh 0.9.6 -

II. Public POCs for CVE-2021-3634

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III. Intelligence Information for CVE-2021-3634

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Vendor Advisories for CVE-2021-3634 (5)

Mailing List Discussions for CVE-2021-3634 (3)

Same Patch Batch · n/a · 2021-08-31 · 33 CVEs total

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CVE-2021-36981 SerNet verinice 代码问题漏洞
CVE-2021-27556 Nature Easy Soft Network Technology ZenTao 操作系统命令注入漏洞
CVE-2021-27557 Nature Easy Soft Network Technology ZenTao 跨站请求伪造漏洞
CVE-2021-27558 Nature Easy Soft Network Technology ZenTao 跨站脚本漏洞
CVE-2021-36356 Kramer Electronics VIAware 代码问题漏洞
CVE-2020-13639 Outsystems OutSystems Platform 跨站脚本漏洞
CVE-2021-38145 Form Tools SQL注入漏洞
CVE-2021-38143 Form Tools 跨站脚本漏洞
CVE-2021-38144 Form Tools 跨站脚本漏洞
CVE-2020-19046 S-CMS 跨站脚本漏洞
CVE-2020-19047 iWebShop 跨站请求伪造漏洞
CVE-2020-19048 MyBB 跨站脚本漏洞
CVE-2020-19049 MyBB 跨站脚本漏洞
CVE-2021-22684 Samsung Galaxy Gear Series Tizen 输入验证错误漏洞
CVE-2020-20495 bludit 安全漏洞
CVE-2021-22943 Ubiquiti Networks UniFi Protect 授权问题漏洞
CVE-2021-22929 Brave 日志信息泄露漏洞
CVE-2021-21811 AT&T Labs Xmill 数字错误漏洞

Showing top 20 of 33 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: libssh
Same vendor: n/a
Same weakness: CWE-787

V. Comments for CVE-2021-3634

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