CVE-2025-66548

Nextcloud Deck app allows to spoof file extensions by using RTLO characters

CVSS 3.3 LOWEPSS 0.1%CWE-116

Vexday Risk Score

8Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 3.3EPSS 0.1%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

05 Dec 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

Nextcloud Deck is a kanban style organization tool aimed at personal planning and project organization for teams integrated with Nextcloud. Prior to 1.12.7, 1.14.4, and 1.15.1, file extension can be spoofed by using RTLO characters, tricking users into download files with a different extension than what is displayed. This vulnerability is fixed in 1.12.7, 1.14.4, and 1.15.1.

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

Affected products

nextcloud · security-advisories

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References

https://github.com/nextcloud/deck/commit/afa95d3c507465b9d31af7c88c69b76711ef185a https://github.com/nextcloud/deck/pull/6671 https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xjvq-xvr7-xpg6 https://hackerone.com/reports/2326618