CVE-2025-66549 | Nextcloud Desktop discloses information when attempting to lock a file inside a end-to-end encrypted directory

Nextcloud Desktop is the desktop sync client for Nextcloud. Prior to 3.16.5, when trying to manually lock a file inside an end-to-end encrypted directory, the path of the file was sent to the server unencrypted, making it possible for administrators to see it in log files. This vulnerability is fixed in 3.16.5.

Published: 2025-12-05 Last update: 2025-12-09 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-66549 is rated Low Risk (13.7/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.04%). Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-66549

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-06 — 0.04% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-66549

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
2.4 3.1 LOW
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 0.9 1.4 [email protected]
2.7 3.1 LOW
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.2 1.4 [email protected]

Weakness enumeration for CVE-2025-66549

OS Trackers for CVE-2025-66549

vendor priority summary link
debian not yet assigned CVE-2025-66549 not yet assigned priority: Debian including 1 source packages (nextcloud-desktop), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2025-66549
ubuntu medium CVE-2025-66549 medium priority: Ubuntu including 1 source packages (nextcloud-desktop), 6 status rows across 6 suites (focal, jammy, noble, plucky, questing, upstream): needs-triage 3, ignored 1, not-affected 1, released 1. https://ubuntu.com/security/CVE-2025-66549

Affected software / configurations for CVE-2025-66549

Vendor Product Version Raw CPE
nextcloud desktop >= 3.0.0, < 3.16.5 cpe:2.3:a:nextcloud:desktop:*:*:*:*:*:*:*:*

References for CVE-2025-66549

cvelogic Threat Intelligence