CVE-2023-48306: Nextcloud Server DNS pin middleware can be tricked into DNS rebinding allowing SSRF

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-11-21 · updated 2026-06-17
Weakness: CWE-918

Description

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.11, 26.0.6, and 27.1.0 of Nextcloud Server and starting in version 22.0.0 and prior to versions 22.2.10.16, 23.0.12.11, 24.0.12.7, 25.0.11, 26.0.6, and 27.1.0 of Nextcloud Enterprise Server, the DNS pin middleware was vulnerable to DNS rebinding allowing an attacker to perform SSRF as a final result. Nextcloud Server 25.0.11, 26.0.6, and 27.1.0 and Nextcloud Enterprise Server 22.2.10.16, 23.0.12.11, 24.0.12.7, 25.0.11, 26.0.6, and 27.1.0 contain patches for this issue. No known workarounds are available.

Affected products

Nextcloud Server: from 22.0.0 before 22.2.10.16; from 23.0.0 before 23.0.12.11; from 24.0.0 before 24.0.12.7; from 25.0.0 before 25.0.11; from 26.0.0 before 26.0.6; from 27.0.0 before 27.1.0 — fixed in 22.2.10.16, 23.0.12.11, 24.0.12.7, 25.0.11, 26.0.6, 27.1.0

How to fix

Upgrade to a fixed version: Nextcloud Server 22.2.10.16, 23.0.12.11, 24.0.12.7, 25.0.11. Check the vendor advisory for mitigations.

References

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