Vulnerability · Published Dec 5, 2025 · Assigned by GitHub_M

CVE-2025-66548Nextcloud Deck app allows to spoof file extensions by using RTLO characters

Low 3.3

In plain English

A low-severity security flaw in security-advisories from nextcloud. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities).

Severity (CVSS 3.1)3.3Low

Exploit odds (30 days)0.2%top 94.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
nextcloud	security-advisories	>= 1.15.0-beta.1, < 1.15.1>= 1.14.0-beta.1, < 1.14.4< 1.12.7

Weakness: CWE-116 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

References

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