Nextcloud Server users can make external storage mount points inaccessible for other users
Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Server and starting in version 20.0.0 and prior to versions 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Enterprise Server, a malicious user could update any personal or global external storage, making them inaccessible for everyone else as well. Nextcloud Server 25.0.13, 26.0.8, and 27.1.3 and Nextcloud Enterprise Server is upgraded to 20.0.14.16, 21.0.9.13, 22.2.10.15, 23.0.12.12, 24.0.12.8, 25.0.13, 26.0.8, and 27.1.3 contain a patch for this issue. As a workaround, disable app files_external. This workaround also makes the external storage inaccessible but retains the configurations until a patched version has been deployed.
Noroxi analysis
No Noroxi analysis for this record yet
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We use this product, ask for help- Published
- Nov 21, 2023
- Updated
- Jun 17, 2026
- EPSS
- 1.0% · 60th percentile
- CWE
- CWE-284
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Report tools
Action score
28
Monitor
Low priority for now.
- CVSS
- 28 / 40 · 7.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.0%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 7.1
- CNA · GitHub_M
- 8.5
- 1.4 point gap
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| nextcloud | nextcloud server | cpe:2.3:a:nextcloud:nextcloud_server |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- nextcloud nextcloud server20.0.0 and later · before 20.0.14.16
- nextcloud nextcloud server21.0.0 and later · before 21.0.9.13
- nextcloud nextcloud server22.0.0 and later · before 22.2.10.15
- nextcloud nextcloud server23.0.0 and later · before 23.0.12.12
- nextcloud nextcloud server24.0.0 and later · before 24.0.12.8
- nextcloud nextcloud server25.0.0 and later · before 25.0.13
- nextcloud nextcloud server26.0.0 and later · before 26.0.8
- nextcloud nextcloud server27.0.0 and later · before 27.1.3
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
nextcloud security-advisories
- >= 25.0.0, < 25.0.13, >= 26.0.0, < 26.0.8, >= 27.0.0, < 27.1.3, >= 20.0.0, < 20.0.14.16, >= 21.0.0, < 21.0.9.13, >= 22.0.0, < 22.2.10.15, >= 23.0.0, < 23.0.12.12, >= 24.0.0, < 24.0.12.8affected
Same product
nextcloud: all recordsOther highest-scoring records for the same primary product.
- CVE-2021-32802Preview generation used third-party library not suited for user-generated content in Nextcloud server40Plan
- CVE-2021-32726Webauthn tokens not removed after user has been deleted40Plan
- CVE-2021-22915Nextcloud server before 19.0.11, 20.0.10, 21.0.2 is vulnerable to brute force attacks due to lack of inclusion of IPv6 subnets in rate-limit40Plan
- CVE-2023-49792Bruteforce protection can be bypassed with misconfigured proxy39Monitor
- CVE-2023-48306Nextcloud Server DNS pin middleware can be tricked into DNS rebinding allowing SSRF39Monitor
- CVE-2021-32654Attacker can obtain write access to any federated share/public link37Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2023-35927151 days apartNextcloud system addressbooks can be modified by malicious trusted server32Monitor
- CVE-2024-37882206 days apartNextcloud Server can reshare read&share only folder with more permissions32Monitor
- CVE-2023-39963103 days apartMissing password confirmation when creating app passwords31Monitor
- CVE-2023-39962103 days apartUsers can delete external storage mount points30Monitor
- CVE-2023-25821270 days apartNextcloud download permissions can be changed by resharer30Monitor
- CVE-2023-39952103 days apartAdvanced permissions not respected when copying entire group folders26Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- low · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- Low
- Availability impact
- High
Weakness class (CWE)
CWE-284 · Improper Access ControlCVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Embedding Scripts within ScriptsCAPEC-19likelihood: High · High
- Malicious Logic InsertionCAPEC-441likelihood: Medium · High
- Modification of Windows Service ConfigurationCAPEC-478likelihood: Low · High
- Malicious Root CertificateCAPEC-479likelihood: Low · Low
- Intent SpoofCAPEC-502
- WebView ExposureCAPEC-503
- Data Injected During ConfigurationCAPEC-536likelihood: Low · High
- Incomplete Data Deletion in a Multi-Tenant EnvironmentCAPEC-546likelihood: Low · Medium
ATT&CK techniques
- RootkitT1014
- Obfuscated Files or Information: Embedded PayloadsT1027.009
- Boot or Logon Initialization ScriptsT1037
- Taint shared contentT1080
- Server Software Component: Terminal Services DLLT1505.005
- Pre-OS Boot:BootkitT1542.003
- Create or Modify System ProcessT1543
- Create or Modify System Process: Launch AgentT1543.001
- Create or Modify System Process:Windows ServiceT1543.003
- Create or Modify System Process: Launch DaemonT1543.004
- Event Triggered Execution:Change Default File AssociationT1546.001
- Event Triggered Execution:.bash_profile and .bashrcT1546.004
- Event Triggered Execution: Accessibility FeaturesT1546.008
- Event Triggered Execution: Installer PackagesT1546.016
- Boot or Logon Autostart ExecutionT1547
- Boot or Logon Autostart Execution:Kernel Modules and ExtensionsT1547.006
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- github.com/nextcloud/security-advisories/security/advisories/GHSA-f962-hw26-g267
- github.com/nextcloud/server/pull/41123
Vendor advisories and official records. Exploit/PoC links are deliberately left out.