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Nextcloud ServerApplication · Nextcloud

CVE-2023-49792

CRITICAL · 9.8 CVSS v3.1 Published 2023-12-22
Fix available
A fix is available. Upgrade to 23.0.12.13 / 24.0.12.9 or later.
See remediation →
100/100
Remediation priority · Urgent
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. In Nextcloud Server prior to versions 26.0.9 and 27.1.4; as well as Nextcloud Enterprise Server prior to versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4; when a (reverse) proxy is configured as trusted proxy the server could be tricked into reading a wrong remote address for an attacker, allowing them executing authentication attempts than intended. Nextcloud Server versions 26.0.9 and 27.1.4 and Nextcloud Enterprise Server versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4 contain a patch 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

A detailed technical summary for this CVE is being prepared.

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:>= 23.0.0, < 23.0.12.13>= 24.0.0, < 24.0.12.9>= 25.0.0, < 25.0.13.4>= 26.0.0, < 26.0.9>= 27.0.0, < 27.1.4

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 23.0.12.13 / 24.0.12.9 / 25.0.13.4 or later
Fixed in 23.0.12.1324.0.12.925.0.13.4
Vendor patch github.com →
Recommended fix High confidence

Upgrade to the latest patch in your current major version line: 23.0.12.13 for v23, 24.0.12.9 for v24, 25.0.13.4 for v25, 26.0.9 for v26, or 27.1.4 for v27

  1. 1. Identify the currently installed Nextcloud Server version via the web UI (Settings > Administration > General) or occ commands
  2. 2. Create a full backup of the Nextcloud database and data directory before proceeding with the upgrade
  3. 3. Put Nextcloud into maintenance mode: sudo -u www-data php occ maintenance:mode --on
  4. 4. Download the appropriate fixed version for your current installation branch
  5. 5. Upgrade to the fixed version: For 23.x line, upgrade to 23.0.12.13; for 24.x line, upgrade to 24.0.12.9; for 25.x line, upgrade to 25.0.13.4; for 26.x line, upgrade to 26.0.9; for 27.x line, upgrade to 27.1.4
  6. 6. Run database migration: sudo -u www-data php occ upgrade
  7. 7. Clear the application cache: sudo -u www-data php occ maintenance:repair
  8. 8. Disable maintenance mode: sudo -u www-data php occ maintenance:mode --off
Caveat Major version upgrades (e.g., 26 to 27) may require additional migration steps and compatibility checks for apps; ensure all third-party apps are compatible with the target version before upgrading

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 $2,300. 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-2023-49792 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data