How severe is CVE-2023-39963?

CVE-2023-39963 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.

Is CVE-2023-39963 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-39963?

CVE-2023-39963 primarily affects Nextcloud Nextcloud Server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-39963?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2023-39963 published?

CVE-2023-39963 was published on 2023-08-10 and last updated on 2026-06-17.

CVE-2023-39963

CVE-2023-39963 is a high-severity vulnerability in Nextcloud Nextcloud Server with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-284.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-284
Affected product: Nextcloud Nextcloud Server
Published: 2023-08-10
Last modified: 2026-06-17

Description

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 20.0.0 and prior to versions 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, a missing password confirmation allowed an attacker, after successfully stealing a session from a logged in user, to create app passwords for the victim. Nextcloud server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.

Frequently asked questions

What is CVE-2023-39963?: Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 20.0.0 and prior to versions 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, a missing password confirmation allowed an attacker, after successfully stealing a session from a logged in user, to create app passwords for the victim. Nextcloud server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 20.0.14.15, 21.0.9.13, 22.2.10.14, 23.0.12.9, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.
How severe is CVE-2023-39963?: CVE-2023-39963 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2023-39963 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-39963?: CVE-2023-39963 primarily affects Nextcloud Nextcloud Server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-39963?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-39963 published?: CVE-2023-39963 was published on 2023-08-10 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:27.0.0:*:*:*:-:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:27.0.0:*:*:*:enterprise:*:*:*

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