CVE-2025-66548
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-05

Last updated on: 2025-12-09

Assigner: GitHub, Inc.

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.
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Meta Information
Published
2025-12-05
Last Modified
2025-12-09
Generated
2026-06-16
AI Q&A
2025-12-05
EPSS Evaluated
2026-06-14
NVD
CVE-2025-66548
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
nextcloud deck to 1.12.7 (exc)
nextcloud deck From 1.14.0 (inc) to 1.14.4 (exc)
nextcloud deck From 1.15.0 (inc) to 1.15.1 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-116 The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
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Executive Summary

This vulnerability in Nextcloud Deck allows an attacker to spoof file extensions by using Right-To-Left Override (RTLO) characters. This tricks users into downloading files that appear to have a different extension than they actually do, potentially misleading them about the file type.

Impact Analysis

The impact of this vulnerability is that users may be tricked into downloading and opening files with misleading extensions, which could lead to executing malicious files or exposing the system to security risks. However, the CVSS score indicates a low severity with limited impact on confidentiality and no impact on availability.

Mitigation Strategies

Update Nextcloud Deck to version 1.12.7, 1.14.4, or 1.15.1 or later, as these versions contain the fix for the RTLO character file extension spoofing vulnerability.

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