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CVE-2021-32679— Filenames not escaped by default in controllers using DownloadResponse

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 Server 中存在输入验证错误漏洞，该漏洞源于 DownloadResponse 没有对上传文件名做安全检查，攻击者可通过该漏洞诱导用户下载具有正常文件名的恶意文件。以下产品及版本受到影响： Nextcloud Server 19.0.13 之前版本、20.0.11 之前版本、21.0.3 之前版本

CVSS 3.5 · Low EPSS 1.37% · P69
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I. Basic Information for CVE-2021-32679

Vulnerability Information
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Vulnerability Title
Filenames not escaped by default in controllers using DownloadResponse
Source: CVE Program / CVE List V5
Vulnerability Description
Nextcloud Server is a Nextcloud package that handles data storage. In versions prior to 19.0.13, 20.0.11, and 21.0.3, filenames where not escaped by default in controllers using `DownloadResponse`. When a user-supplied filename was passed unsanitized into a `DownloadResponse`, this could be used to trick users into downloading malicious files with a benign file extension. This would show in UI behaviours where Nextcloud applications would display a benign file extension (e.g. JPEG), but the file will actually be downloaded with an executable file extension. The vulnerability is patched in versions 19.0.13, 20.0.11, and 21.0.3. Administrators of Nextcloud instances do not have a workaround available, but developers of Nextcloud apps may manually escape the file name before passing it into `DownloadResponse`.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对输出编码和转义不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Nextcloud 输入验证错误漏洞
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 Server 中存在输入验证错误漏洞，该漏洞源于 DownloadResponse 没有对上传文件名做安全检查，攻击者可通过该漏洞诱导用户下载具有正常文件名的恶意文件。以下产品及版本受到影响： Nextcloud Server 19.0.13 之前版本、20.0.11 之前版本、21.0.3 之前版本
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 < 19.0.13 -

II. Public POCs for CVE-2021-32679

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III. Intelligence Information for CVE-2021-32679

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Patches & Fixes for CVE-2021-32679 (1)

Vendor Advisories for CVE-2021-32679 (2)

Mailing List Discussions for CVE-2021-32679 (2)

Other References for CVE-2021-32679 (1)

Same Patch Batch · nextcloud · 2021-07-12 · 14 CVEs total

CVE-2021-32688 8.8 HIGH Application specific tokens can change their own scope
CVE-2021-32689 8.1 HIGH Nextcloud Talk not properly disassociating users from chats after account deletion
CVE-2021-32726 7.1 HIGH Webauthn tokens not removed after user has been deleted
CVE-2021-32727 5.7 MEDIUM End-to-end encryption device setup did not verify public key
CVE-2021-32741 5.3 MEDIUM Lack of ratelimit on public share link mount endpoint
CVE-2021-32705 5.3 MEDIUM Lack of ratelimit on public DAV endpoint
CVE-2021-32703 5.3 MEDIUM Lack of ratelimit on shareinfo endpoint
CVE-2021-32733 4.8 MEDIUM XSS in Nextcloud Text application
CVE-2021-32707 4.3 MEDIUM Bypass of image blocking in Nextcloud Mail
CVE-2021-32678 3.7 LOW Ratelimit not applied on OCS API responses
CVE-2021-32725 3.5 LOW Default share permissions not respected for federated reshares
CVE-2021-32680 3.3 LOW Audit log is not properly logging unsetting of share expiration date
CVE-2021-32734 3.1 LOW File path disclosure of shared files in Nextcloud Text application

IV. Related Vulnerabilities

Same product: security-advisories
Same vendor: nextcloud
Same weakness: CWE-116

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