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Nextcloud ServerApplication · Nextcloud

CVE-2023-48306

CRITICAL · 9.8 CVSS v3.1 Published 2023-11-21
Fix available
A fix is available. Upgrade to 22.2.10.16 / 23.0.12.11 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-918

The server can be induced to make requests to a URL an attacker controls, turning it into a proxy into internal networks and cloud metadata services. It's especially dangerous behind a trusted network boundary. The fix is strict allow-listing of destinations and blocking access to internal address ranges.

General guidance for the server-side request forgery (ssrf) class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Nextcloud ServerApplication
Affected:>= 22.0.0, < 22.2.10.16>= 23.0.0, < 23.0.12.11>= 24.0.0, < 24.0.12.7>= 25.0.0, < 25.0.11>= 26.0.0, < 26.0.6>= 27.0.0, < 27.1.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 22.2.10.16 / 23.0.12.11 / 24.0.12.7 or later
Fixed in 22.2.10.1623.0.12.1124.0.12.7
Vendor patch github.com →
Recommended fix High confidence

Upgrade to Nextcloud Server 25.0.11 (if on v25), 26.0.6 (if on v26), or 27.1.0 (if on v27). Ideally upgrade to the latest stable 27.x release.

  1. 1. Identify the current Nextcloud Server version by checking the admin settings or config/version.php file
  2. 2. Determine the appropriate upgrade path based on current version (see upgrade_path field)
  3. 3. Create a complete backup of the Nextcloud database, data directory, and configuration files
  4. 4. Stop the Nextcloud web server or put the server in maintenance mode
  5. 5. Follow Nextcloud's official upgrade documentation to upgrade to the target fixed version
  6. 6. Run the occ maintenance:data-fingerprint command if prompted after upgrade
  7. 7. Verify the upgrade was successful by checking the version in admin settings
  8. 8. Ensure the DNS pin middleware is functioning correctly by testing affected functionality
Caveat Minor version upgrades within the same major version (e.g., 25.0.0 to 25.0.11) typically have no breaking changes. However, upgrading across major versions may require reviewing Nextcloud's migration notes and checking app compatibility.

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,550. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-48306 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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