CVE-2025-66545VulnerabilityPublished 5 Dec 2025Updated 8 Dec 2025

CVE-2025-66545: nextcloud security-advisories · Improper Neutralization

Affects nextcloud security-advisoriesSource CVE Database V5

Not known to be exploited · CVSS 3.5 Low : upgrade to 14.0.11 when convenient.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

3.5Low

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 14.0.11

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade nextcloud/groupfolders to 14.0.11.

Affected software

Product	Affected	Fixed in
GitHubnextcloud/groupfolders`pkg:github/nextcloud/groupfolders`Other threats	Affected <14.0.11	Fixed in 14.0.11

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Upgrade all Nextcloud Groupfolders installations to the fixed versions: 14.0.11, 15.3.12, 16.0.15, 17.0.14, 18.1.8, 19.1.8, or 20.1.2, depending on the version in use. 2. Conduct a thorough audit of groupfolder permissions to ensure that read-only users do not have unintended capabilities. 3. Implement monitoring and alerting on file restoration activities within group folders to detect unauthorized restorations promptly. 4. Educate administrators and users about the importance of permission hygiene and the risks of improper file restoration. 5. Consider deploying additional access controls or logging mechanisms to track changes in shared folders. 6. Review and update incident response plans to include scenarios involving unauthorized file restorations. 7. If upgrading immediately is not feasible, restrict access to the trash bin functionality or disable groupfolder features temporarily as a stopgap measure. 8.

Description

Nextcloud Groupfolders provides admin-configured folders shared by everyone in a group or team. Prior to 14.0.11, 15.3.12, 16.0.15, 17.0.14, 18.1.8, 19.1.8, and 20.1.2, a user with read-only permission can restore a file from the trash bin. This vulnerability is fixed in 14.0.11, 15.3.12, 16.0.15, 17.0.14, 18.1.8, 19.1.8, and 20.1.2.

Impact

For European organizations, the primary impact of CVE-2025-66545 is on data integrity within shared group folders managed by Nextcloud. Unauthorized restoration of deleted files by read-only users could lead to reintroduction of outdated, corrupted, or malicious files, potentially disrupting workflows or causing confusion. Although confidentiality and availability are not directly affected, the integrity breach could undermine trust in shared data and complicate audit trails. Organizations in sectors with strict data governance, such as finance, healthcare, and government, may face compliance risks if unauthorized file restorations go undetected. The low CVSS score and absence of known exploits reduce immediate risk, but the widespread use of Nextcloud in Europe means many organizations could be exposed if patches are not applied. Attackers with limited privileges could exploit this vulnerability to bypass intended access controls, emphasizing the need for timely remediation.

CWE-707Improper Neutralization (opens in a new tab)
Pillar weakness
The product does not ensure or incorrectly ensures that structured messages or data are well-formed and that certain security properties are met before being read from an upstream component or sent to a downstream component.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
Attack patterns
XML Injection (opens in a new tab)
Inter-component Protocol Manipulation (opens in a new tab)
Data Interchange Protocol Manipulation (opens in a new tab)
Web Services Protocol Manipulation (opens in a new tab)
SOAP Manipulation (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Dec 2025, 19:08 UTC

WeaknessesCWE-707

Technical details

References

Community reviews

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