High severity · published Oct 27, 2026
CVE-2026-77167
Abusing the federated share endpoint, an attacker can write arbitrary rows into the oc_share_external database table
New
7.5
CVSS
–
EPSS
No
On KEV
Description
Abusing the federated share endpoint, an attacker can write arbitrary rows into the oc_share_external database table. These rows persist indefinitely — there is no automatic cleanup mechanism. Three distinct denial-of-service conditions follow from this write primitive, all triggered from the same unauthenticated source and all self-renewing on a 24-hour cycle for as long as the injected rows remain in the database.
CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SE
server · Nextcloud
22.0.0 through 34.0.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-77167
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-77167
hackerone.com
https://hackerone.com/reports/3679640
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