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
0.3%
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?
Exploit prediction (EPSS)0.3% · higher than 25% of CVEs
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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