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CVE-2023-49105: ownCloud Improper Authentication Vulnerability

97
Patch now
CRITICAL 9.8EXPLOITEDREMOTEUPGRADE

CVE-2023-49105 is a critical-severity flaw (CVSS 9.8) affecting owncloud server, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in ownCloud owncloud/core before 10.13.1. An attacker can access, modify, or delete any file without authentication if the username of a victim is known, and the victim has no signing-key configured. This occurs because pre-signed URLs can be accepted even when no signing-key is configured for the owner of the files. The earliest affected version is 10.6.0.

Why this priority

  • Critical severity
  • EPSS top 1%: very likely to be exploited
  • Exploited in the wild (CISA KEV)
  • Public exploit reference
  • CISA SSVC: automatable with total technical impact
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score9.8 (Critical)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance43.2% (top 1%)
CISA exploited listYes, fix due 2026-08-30
WeaknessCWE-287
Published2023-11-21
Last modified2026-08-28
Publisher (CNA): MITRE · Vendor: owncloud

Am I affected?

Timeline

owncloud owncloud server UPGRADE
Affected: >= 10.6.0 and < 10.13.1
Fixed in: 10.13.1
Safe to downgrade to: a release before 10.6.0
1. Check installed version
apt-cache policy owncloud-server || rpm -q owncloud-server || owncloud-server --version
2. UPGRADE to 10.13.1 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade owncloud-server
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade owncloud-server
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 10.6.0 (Debian / Ubuntu)
apt-cache madison owncloud-server sudo apt install owncloud-server=<VERSION_BEFORE_10.6.0> sudo apt-mark hold owncloud-server
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list owncloud-server sudo dnf downgrade owncloud-server-<VERSION_BEFORE_10.6.0> sudo dnf versionlock add owncloud-server
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora 46 · uv · FIXED · 0.13.5-1.fc46 · FEDORA-2026-61ea5a28c6 · source
sudo dnf upgrade --advisory=FEDORA-2026-61ea5a28c6

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-49105?

owncloud server: upgrade to 10.13.1. Exact commands for each OS are on this page.

Is CVE-2023-49105 being exploited?

Yes. CVE-2023-49105 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2023-49105 affect?

CVE-2023-49105 affects owncloud server. Severity is critical (CVSS 9.8). An issue was discovered in ownCloud owncloud/core before 10.13.1. An attacker can access, modify, or delete any file without authentication if the username of a victim is known, and the victim has no signing-key configured. This occurs beca

How urgent is CVE-2023-49105?

Priority 97/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

References

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