Nextcloud Server before 9.0.54 and 10.0.0 suffers from an improper authorization check on removing shares.
Nextcloud Server before 9.0.54 and 10.0.0 suffers from an improper authorization check on removing shares. The Sharing Backend as implemented in Nextcloud does differentiate between shares to users and groups. In case of a received group share, users should be able to unshare the file to themselves but not to the whole group. The previous API implementation simply unshared the file to all users in the group.
- Published
- Mar 27, 2017
- Updated
- Jun 16, 2026
- EPSS
- 1.6% · 75th percentile
- CWE
- CWE-285
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Report tools
Action score
17
Monitor
Low priority for now.
- CVSS
- 17 / 40 · 4.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.6%
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 serverbefore 9.0.54
- nextcloud nextcloud server10.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (hackerone). Independent of NVD's CPE analysis and usually ahead of it.
n/a Nextcloud Server Nextcloud Server before 9.0.54 and 10.0.0
- Nextcloud Server Nextcloud Server before 9.0.54 and 10.0.0affected
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.
No nightly-computed relations.
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
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- Low
- Availability impact
- None
Weakness class (CWE)
CWE-285 · Improper AuthorizationCVSS vector
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
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)
- Accessing Functionality Not Properly Constrained by ACLsCAPEC-1likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Directory IndexingCAPEC-127likelihood: High · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
- Using Malicious FilesCAPEC-17likelihood: High · Very High
- Manipulating Opaque Client-based Data TokensCAPEC-39likelihood: High · Medium
- Bypassing ATA Password SecurityCAPEC-402
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
ATT&CK techniques
- Data from Local SystemT1005
- Query RegistryT1012
- File and Directory DiscoveryT1083
- Access Token Manipulation:Token Impersonation/TheftT1134.001
- Use Alternate Authentication Material:Web Session CookieT1550.004
- Unsecured Credentials: Credentials in RegistryT1552.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Data Manipulation: Transmitted Data ManipulationT1565.002
- Hijack Execution Flow: Executable Installer File Permissions WeaknessT1574.005
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
- Hijack Execution Flow: ServicesFile Permissions WeaknessT1574.010
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- www.securityfocus.com/bid/97287
- github.com/nextcloud/server/commit/3387e5d00fcf6b2ea6b285a091e5743f545e7202
- github.com/nextcloud/server/commit/7289cb5ec0b812992ab0dfb889744b94bc0994f0
- github.com/nextcloud/server/commit/a5471b4a3e3f30e99e4de39c97c0c3b3c2f1618f
- github.com/nextcloud/server/commit/e2c4f4f9aa11bc92e8f2212cce73841b922187e8
- nextcloud.com/security/advisory/?id=nc-sa-2016-007
Vendor advisories and official records. Exploit/PoC links are deliberately left out.