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CVE-2021-4120— snapd could be made to bypass intended access restrictions through snap content interfaces and layout paths

Quick assessment

Affected
Canonical Ltd. snapd
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Snapd是开源的一个跨平台的包管理工具。 snapd 2.54.2版本存在安全漏洞，该漏洞源于软件未能对snap内容界面和布局路径执行充分的验证，导致snap能够通过变形的内容界面和布局声明注入任意的AppArmor策略规则，从而逃脱严格的snap限制。

CVSS 8.2 · High EPSS 0.44% · P36

Possible ATT&CK Techniques 1 AI

T1548.003 · Sudo and Sudo Caching
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I. Basic Information for CVE-2021-4120

Vulnerability Information
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Vulnerability Title
snapd could be made to bypass intended access restrictions through snap content interfaces and layout paths
Source: CVE Program / CVE List V5
Vulnerability Description
snapd 2.54.2 fails to perform sufficient validation of snap content interface and layout paths, resulting in the ability for snaps to inject arbitrary AppArmor policy rules via malformed content interface and layout declarations and hence escape strict snap confinement. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Snapd 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Snapd是开源的一个跨平台的包管理工具。 snapd 2.54.2版本存在安全漏洞，该漏洞源于软件未能对snap内容界面和布局路径执行充分的验证，导致snap能够通过变形的内容界面和布局声明注入任意的AppArmor策略规则，从而逃脱严格的snap限制。
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
Canonical Ltd. snapd unspecified ~ 2.54.2 -

II. Public POCs for CVE-2021-4120

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III. Intelligence Information for CVE-2021-4120

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Vendor Advisories for CVE-2021-4120 (1)

Mailing List Discussions for CVE-2021-4120 (2)

Other References for CVE-2021-4120 (1)

Same Patch Batch · Canonical Ltd. · 2022-02-17 · 4 CVEs total

CVE-2021-44730 7.8 HIGH snapd could be made to escalate privileges and run programs as administrator
CVE-2021-44731 7.8 HIGH snapd could be made to escalate privileges and run programs as administrator
CVE-2021-3155 3.8 LOW snapd created ~/snap with too-wide permissions

IV. Related Vulnerabilities

Same product: snapd
Same vendor: Canonical Ltd.
Same weakness: CWE-20

V. Comments for CVE-2021-4120

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