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CVE-2021-39221— XSS in Contacts

Quick assessment

Affected
nextcloud security-advisories
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.

Nextcloud是德国Nextcloud公司的一套开源的自托管文件同步和共享的通信应用平台。 Nextcloud存在安全漏洞，该漏洞源于WEB应用缺少对客户端数据的正确验证。攻击者可利用该漏洞执行客户端代码。

CVSS 6.4 · Medium EPSS 0.52% · P42

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter
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I. Basic Information for CVE-2021-39221

Vulnerability Information
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Vulnerability Title
XSS in Contacts
Source: CVE Program / CVE List V5
Vulnerability Description
Nextcloud is an open-source, self-hosted productivity platform. The Nextcloud Contacts application prior to version 4.0.3 was vulnerable to a stored Cross-Site Scripting (XSS) vulnerability. For exploitation, a user would need to right-click on a malicious file and open the file in a new tab. Due the strict Content-Security-Policy shipped with Nextcloud, this issue is not exploitable on modern browsers supporting Content-Security-Policy. It is recommended that the Nextcloud Contacts application is upgraded to 4.0.3. As a workaround, one may use a browser that has support for Content-Security-Policy.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
危险类型文件的不加限制上传
Source: CVE Program / CVE List V5
Vulnerability Title
Nextcloud 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Nextcloud是德国Nextcloud公司的一套开源的自托管文件同步和共享的通信应用平台。 Nextcloud存在安全漏洞，该漏洞源于WEB应用缺少对客户端数据的正确验证。攻击者可利用该漏洞执行客户端代码。
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
nextcloud security-advisories < 4.0.3 -

II. Public POCs for CVE-2021-39221

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III. Intelligence Information for CVE-2021-39221

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Patches & Fixes for CVE-2021-39221 (1)

Vendor Advisories for CVE-2021-39221 (1)

Same Patch Batch · nextcloud · 2021-10-25 · 8 CVEs total

CVE-2021-41178 8.8 HIGH File Traversal affecting SVG files on Nextcloud Server
CVE-2021-39225 8.1 HIGH Missing permission check on Deck API
CVE-2021-41177 8.1 HIGH Rate-limits not working on instances without configured memory cache backend
CVE-2021-41179 6.5 MEDIUM Two-Factor Authentication not enforced for pages marked as public
CVE-2021-39223 4.8 MEDIUM File path disclosure of shared files in Richdocuments application
CVE-2021-39220 3.5 LOW Bypass of image blocking in Nextcloud Mail
CVE-2021-39224 3.5 LOW File path disclosure of shared files in OfficeOnline application

IV. Related Vulnerabilities

Same product: security-advisories
Same vendor: nextcloud
Same weakness: CWE-434

V. Comments for CVE-2021-39221

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