CVE-2023-39959

Name: CVE-2023-39959
Creator: NVD / NIST
Published: 2023-08-10T18:15:10.157+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.49%

Last modified Jun 17, 2026

CVE-2023-39959 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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. EPSS estimates a 0.49% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS Probability

0.49%

38.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-284

Affected Software

Vendor	Product	Versions
Nextcloud	Nextcloud Server	>= 25.0.0, < 25.0.9
Nextcloud	Nextcloud Server	>= 26.0.0, < 26.0.4
Nextcloud	Nextcloud Server	27.0.0

References

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-g97r-8ffm-hfpjVendor Advisory
https://github.com/nextcloud/server/pull/38747Patch
https://hackerone.com/reports/1832126Permissions Required
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-g97r-8ffm-hfpjVendor Advisory
https://github.com/nextcloud/server/pull/38747Patch
https://hackerone.com/reports/1832126Permissions Required

Timeline

Published: Aug 10, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-39959?

How severe is CVE-2023-39959?

CVE-2023-39959 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.49% probability of exploitation in the next 30 days.

How do I fix CVE-2023-39959?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-39959?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST