CVE-2021-32688— Application specific tokens can change their own scope
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 存在安全漏洞，该漏洞源于Nextcloud Server缺乏权限检查，令牌能够在19.0.13、20.0.11和21.0.3之前的版本中更改它们自己的权限。攻击者可利用该漏洞导致文件系统限制令牌能够授予自己对文件系统的访问权。
Possible ATT&CK Techniques 2 AI
T1556 · Modify Authentication Process T1528 · Steal Application Access Token
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I. Basic Information for CVE-2021-32688
Vulnerability Information
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Vulnerability Title
Application specific tokens can change their own scope
Source: CVE Program / CVE List V5
Vulnerability Description
Nextcloud Server is a Nextcloud package that handles data storage. Nextcloud Server supports application specific tokens for authentication purposes. These tokens are supposed to be granted to a specific applications (e.g. DAV sync clients), and can also be configured by the user to not have any filesystem access. Due to a lacking permission check, the tokens were able to change their own permissions in versions prior to 19.0.13, 20.0.11, and 21.0.3. Thus fileystem limited tokens were able to grant themselves access to the filesystem. The issue is patched in versions 19.0.13, 20.0.11, and 21.0.3. There are no known workarounds aside from upgrading.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Nextcloud 授权问题漏洞
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 Server 存在安全漏洞，该漏洞源于Nextcloud Server缺乏权限检查，令牌能够在19.0.13、20.0.11和21.0.3之前的版本中更改它们自己的权限。攻击者可利用该漏洞导致文件系统限制令牌能够授予自己对文件系统的访问权。
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-2021-32688
| # | POC Description | Source Link | Shenlong Link |
|---|
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Patches & Fixes for CVE-2021-32688 (1)
-
https://github.com/nextcloud/server/pull/27000 x_refsource_MISC
Vendor Advisories for CVE-2021-32688 (2)
Mailing List Discussions for CVE-2021-32688 (2)
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https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J63NBVPR2AQCAWRNDOZSGRY5II4WS2CZ/ vendor-advisory x_refsource_FEDORA
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https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BVZS26RDME2DYTKET5AECRIZDFUGR2AZ/ vendor-advisory x_refsource_FEDORA
Other References for CVE-2021-32688 (1)
-
https://hackerone.com/reports/1193321 x_refsource_MISC
Same Patch Batch · nextcloud · 2021-07-12 · 14 CVEs total
| 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-2021-32679 | 3.5 LOW | Filenames not escaped by default in controllers using DownloadResponse |
| 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 |
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V. Comments for CVE-2021-32688
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