Vulnerability Name:

CVE-2021-32656 (CCN-202909)

Assigned:2021-06-01
Published:2021-06-01
Updated:2022-10-25
Summary:Nextcloud Server is a Nextcloud package that handles data storage. A vulnerability in federated share exists in versions prior to 19.0.11, 20.0.10, and 21.0.2. An attacker can gain access to basic information about users of a server by accessing a public link that a legitimate server user added as a federated share. This happens because Nextcloud supports sharing registered users with other Nextcloud servers, which can be done automatically when selecting the "Add server automatically once a federated share was created successfully" setting. The vulnerability is patched in versions 19.0.11, 20.0.10, and 21.0.2 As a workaround, disable "Add server automatically once a federated share was created successfully" in the Nextcloud settings.
CVSS v3 Severity:8.6 High (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N)
7.5 High (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): High
Integrity (I): None
Availibility (A): None
8.6 High (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N)
7.5 High (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): High
Integrity (I): None
Availibility (A): None
CVSS v2 Severity:5.0 Medium (CVSS v2 Vector: AV:N/AC:L/Au:N/C:P/I:N/A:N)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Authentication (Au): None
Impact Metrics:Confidentiality (C): Partial
Integrity (I): None
Availibility (A): None
7.8 High (CCN CVSS v2 Vector: AV:N/AC:L/Au:N/C:C/I:N/A:N)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): Complete
Integrity (I): None
Availibility (A): None
Vulnerability Type:CWE-284
Vulnerability Consequences:Obtain Information
References:Source: MITRE
Type: CNA
CVE-2021-32656

Source: XF
Type: UNKNOWN
nextcloud-cve202132656-info-disc(202909)

Source: CCN
Type: Nextcloud GIT Repository
Trusted servers exchange can be triggered by attacker

Source: CONFIRM
Type: Third Party Advisory
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-j875-vr2q-h6x6

Source: MISC
Type: Permissions Required, Third Party Advisory
https://hackerone.com/reports/1167853

Source: GENTOO
Type: Third Party Advisory
GLSA-202208-17

Vulnerable Configuration:Configuration 1:
  • cpe:/a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:* (Version < 19.0.11)
  • OR cpe:/a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:* (Version >= 20.0.0 and < 20.0.10)
  • OR cpe:/a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:* (Version >= 21.0.0 and < 21.0.2)

    • Configuration CCN 1:
  • cpe:/a:nextcloud:nextcloud_server:20.0.0:-:*:*:*:*:*:*
  • OR cpe:/a:nextcloud:nextcloud_server:19.0.0:-:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    BACK
    nextcloud nextcloud server *
    nextcloud nextcloud server *
    nextcloud nextcloud server *
    nextcloud nextcloud server 20.0.0
    nextcloud nextcloud server 19.0.0 -