CVE-2025-66548 Nextcloud Deck app allows to spoof file extensions by using RTLO characters
Attackers can spoof file extensions using RTLO characters to trick users into downloading malicious files, requiring an upgrade to the Nextcloud Deck app.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-66548?
CVE-2025-66548 is a low-severity vulnerability in nextcloud security-advisories, published on 5 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-116
Which versions are affected by CVE-2025-66548?
It affects 1 product.
Products include Nextcloud Deck.
How do I fix CVE-2025-66548?
No fix has been published for CVE-2025-66548 yet. Limit exposure of the affected software until one is available.
Is CVE-2025-66548 being exploited?
There is no known exploitation of CVE-2025-66548 in the wild and no public exploit code.
Other vulnerabilities in nextcloud security-advisories
- CVE-2021-39225 Missing permission check on Deck API
- CVE-2020-8182 Missing authorization in Nextcloud Deck
- CVE-2021-37631 Circle can be accessed by non-Circle members in Nextcloud Deck
- CVE-2021-22913 Information disclosure in Nextcloud Deck
- CVE-2023-22469 Nextcloud Deck card vulnerable to data leak to unauthorized users via reference preview cache
Sources
Also known as GHSA-xjvq-xvr7-xpg6.