How severe is CVE-2025-66557?

CVE-2025-66557 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.

Is CVE-2025-66557 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66557?

CVE-2025-66557 affects Nextcloud Deck. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66557?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-66557 have an EU (EUVD) identifier?

Yes. CVE-2025-66557 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201465.

When was CVE-2025-66557 published?

CVE-2025-66557 was published on 2025-12-05 and last updated on 2026-06-17.

CVE-2025-66557

CVE-2025-66557 is a medium-severity vulnerability in Nextcloud Deck with a CVSS 3.x base score of 5.4. 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: Medium (CVSS 3.x base score 5.4)
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201465
Weakness: CWE-284
Affected product: Nextcloud Deck
Published: 2025-12-05
Last modified: 2026-06-17

Description

Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. Prior to 1.14.6 and 1.15.2, a bug in the permission logic allowed users with "Can share" permission to modify the permissions of other recipients. This vulnerability is fixed in 1.14.6 and 1.15.2.

Frequently asked questions

What is CVE-2025-66557?: Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. Prior to 1.14.6 and 1.15.2, a bug in the permission logic allowed users with "Can share" permission to modify the permissions of other recipients. This vulnerability is fixed in 1.14.6 and 1.15.2.
How severe is CVE-2025-66557?: CVE-2025-66557 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.
Is CVE-2025-66557 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66557?: CVE-2025-66557 affects Nextcloud Deck. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66557?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66557 have an EU (EUVD) identifier?: Yes. CVE-2025-66557 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201465.
When was CVE-2025-66557 published?: CVE-2025-66557 was published on 2025-12-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nextcloud:deck:*:*:*:*:*:*:*:*

More vulnerabilities in Nextcloud Deck

CVE-2021-39225 — High (CVSS 8.1): Nextcloud is an open-source, self-hosted productivity platform. A missing permission check in Nextcloud Deck before…
CVE-2020-8182 — High (CVSS 8.0): Improper access control in Nextcloud Deck 0.8.0 allowed an attacker to reshare boards shared with them with more…
CVE-2021-37631 — Medium (CVSS 6.5): Deck is an open source kanban style organization tool aimed at personal planning and project organization for teams…
CVE-2021-22913 — Medium (CVSS 6.5): Nextcloud Deck before 1.2.7, 1.4.1 suffers from an information disclosure vulnerability when searches for sharees…
CVE-2023-22469 — Medium (CVSS 5.8): Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with…
CVE-2022-29159 — Medium (CVSS 5.0): Nextcloud Deck is a Kanban-style project & personal management tool for Nextcloud. In versions prior to 1.4.8, 1.5.6,…

All CVEs affecting Nextcloud Deck →

Other CWE-284 (Improper Access Control) vulnerabilities

CVE-2026-76607 — Critical (CVSS 10.0): Joomla Extension - fabrikar.com - Missing ACL check in download element in Fabrik < 4.7.3 - ???.
CVE-2026-20315 — Critical (CVSS 10.0): As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Workload engineering…
CVE-2026-70921 — Critical (CVSS 10.0): Vulnerability in the Oracle Hyperion Financial Management product of Oracle Hyperion (component: Security). The…
CVE-2026-66803 — Critical (CVSS 10.0): Improper access control in Azure Cosmos DB allows an unauthorized attacker to execute code over a network.
CVE-2026-58630 — Critical (CVSS 10.0): Improper access control in Azure App Service allows an unauthorized attacker to elevate privileges over a network.
CVE-2026-60358 — Critical (CVSS 10.0): Vulnerability in the Oracle Access Manager product of Oracle Fusion Middleware (component: Authentication Engine).…

Browse all CWE-284 (Improper Access Control) vulnerabilities →