CVE-2025-66548

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

MEDIUM
5.5
CVSS Score
Published: December 5, 2025 at 05:26 PM UTC
Updated: October 15, 2026 at 09:10 PM UTC
2 products affected across 1 vendorDecksecurity-advisories

Using security-advisories by nextcloud?

Get instant alerts when new vulnerabilities affect security-advisories - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Deck· Nextcloudnextcloud-app
95%
All versionsv < 1.12.71.14.0 ≤ v < 1.14.41.15.0 ≤ v < 1.15.1

References (4)

x_refsource_MISCIssue Tracking
Source: cverecord
https://github.com/nextcloud/deck/pull/6671
x_refsource_MISCPermissions RequiredVendor Advisory
Source: cverecord
https://hackerone.com/reports/2326618

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-116

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card