5.5
MEDIUM CVSS 3.1
CVE-2025-66548
Nextcloud Deck app allows to spoof file extensions by using RTLO characters
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.

INFO

Published Date :

Dec. 5, 2025, 6:15 p.m.

Last Modified :

Dec. 9, 2025, 7:01 p.m.

Remotely Exploit :

No
Affected Products

The following products are affected by CVE-2025-66548 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Nextcloud deck
2 Nextcloud notes
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 LOW [email protected]
CVSS 3.1 LOW MITRE-CVE
CVSS 3.1 MEDIUM [email protected]
Solution
Update Nextcloud Deck to a version that includes the fix for file extension spoofing.
  • Update Nextcloud Deck to 1.12.7 or later.
  • Update Nextcloud Deck to 1.14.4 or later.
  • Update Nextcloud Deck to 1.15.1 or later.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-66548.

URL Resource
https://github.com/nextcloud/deck/commit/afa95d3c507465b9d31af7c88c69b76711ef185a Patch
https://github.com/nextcloud/deck/pull/6671 Issue Tracking
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xjvq-xvr7-xpg6 Patch Vendor Advisory
https://hackerone.com/reports/2326618 Permissions Required Vendor Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-66548 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-66548 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-66548 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2025-66548 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Dec. 09, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
    Added CPE Configuration OR *cpe:2.3:a:nextcloud:deck:*:*:*:*:*:*:*:* versions up to (excluding) 1.12.7 *cpe:2.3:a:nextcloud:deck:*:*:*:*:*:*:*:* versions from (including) 1.14.0 up to (excluding) 1.14.4 *cpe:2.3:a:nextcloud:deck:*:*:*:*:*:*:*:* versions from (including) 1.15.0 up to (excluding) 1.15.1
    Added Reference Type GitHub, Inc.: https://github.com/nextcloud/deck/commit/afa95d3c507465b9d31af7c88c69b76711ef185a Types: Patch
    Added Reference Type GitHub, Inc.: https://github.com/nextcloud/deck/pull/6671 Types: Issue Tracking
    Added Reference Type GitHub, Inc.: https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xjvq-xvr7-xpg6 Types: Patch, Vendor Advisory
    Added Reference Type GitHub, Inc.: https://hackerone.com/reports/2326618 Types: Permissions Required, Vendor Advisory
  • New CVE Received by [email protected]

    Dec. 05, 2025

    Action Type Old Value New Value
    Added 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.
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
    Added CWE CWE-116
    Added Reference https://github.com/nextcloud/deck/commit/afa95d3c507465b9d31af7c88c69b76711ef185a
    Added Reference https://github.com/nextcloud/deck/pull/6671
    Added Reference https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xjvq-xvr7-xpg6
    Added Reference https://hackerone.com/reports/2326618
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 5.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact