CVE-2023-39959

Existence of calendars and address books can be checked by unauthenticated users

Severity Score

5.3

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.9, 26.0.4, and 27.0.1, unauthenticated users could send a DAV request which reveals whether a calendar or an address book with the given identifier exists for the victim. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.

*Credits: N/A

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

None

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2023-08-07 CVE Reserved
2023-08-10 CVE Published
2024-10-08 CVE Updated
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-284: Improper Access Control

CAPEC

References (2)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC
https://github.com/nextcloud/server/pull/38747	2023-08-16

URL	Date	SRC
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-g97r-8ffm-hfpj	2023-08-16

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Nextcloud Search vendor "Nextcloud"		Nextcloud Server Search vendor "Nextcloud" for product "Nextcloud Server"				>= 25.0.0 < 25.0.9 Search vendor "Nextcloud" for product "Nextcloud Server" and version " >= 25.0.0 < 25.0.9"		-		Affected
Nextcloud Search vendor "Nextcloud"		Nextcloud Server Search vendor "Nextcloud" for product "Nextcloud Server"				>= 25.0.0 < 25.0.9 Search vendor "Nextcloud" for product "Nextcloud Server" and version " >= 25.0.0 < 25.0.9"		enterprise		Affected
Nextcloud Search vendor "Nextcloud"		Nextcloud Server Search vendor "Nextcloud" for product "Nextcloud Server"				>= 26.0.0 < 26.0.4 Search vendor "Nextcloud" for product "Nextcloud Server" and version " >= 26.0.0 < 26.0.4"		-		Affected
Nextcloud Search vendor "Nextcloud"		Nextcloud Server Search vendor "Nextcloud" for product "Nextcloud Server"				>= 26.0.0 < 26.0.4 Search vendor "Nextcloud" for product "Nextcloud Server" and version " >= 26.0.0 < 26.0.4"		enterprise		Affected
Nextcloud Search vendor "Nextcloud"		Nextcloud Server Search vendor "Nextcloud" for product "Nextcloud Server"				27.0.0 Search vendor "Nextcloud" for product "Nextcloud Server" and version "27.0.0"		-		Affected
Nextcloud Search vendor "Nextcloud"		Nextcloud Server Search vendor "Nextcloud" for product "Nextcloud Server"				27.0.0 Search vendor "Nextcloud" for product "Nextcloud Server" and version "27.0.0"		enterprise		Affected