CVE-2023-49105

ownCloud authentication bypass, confirmed exploited in the wild.

ownCloud contains an improper authentication vulnerability that allows an attacker to access, modify, or delete any file without authentication if the username of a victim is known, and the victim has no signing-key configured.

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43%chance of exploitation in the next 30 days (EPSS), 98th percentile

27 Augadded to CISA's Known Exploited Vulnerabilities list, 2026

30 Augfederal remediation deadline, already passed

Passedpast the deadline: patch now

CISA's name for it	ownCloud Improper Authentication Vulnerability
Vendor and product	ownCloud · ownCloud
Type	authentication bypass · CWE-287
Exploited	Confirmed by CISA listed 27 August 2026
Likelihood	one of the most likely to be exploited of every vulnerability tracked
Deadline	30 August 2026 · already passed
Used in ransomware	Not reported
Advisories	owncloud.org ↗ · owncloud.com ↗ · www.cisa.gov ↗ · www.cisa.gov ↗

What to do

Three steps, in this order

Step 1

Apply the vendor fix and restart the affected service.

Step 2

Put the login or management interface behind a VPN or allow-list; a bypass makes passwords irrelevant.

Step 3

Rotate credentials and session keys the product holds, and review accounts and configuration changes since the listing date.

CISA's required action	Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

CISA's required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

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Questions

CVE-2023-49105 in short

Is CVE-2023-49105 being exploited?

Yes. CISA added CVE-2023-49105 to its Known Exploited Vulnerabilities catalogue on 27 August 2026, which it does only on evidence of exploitation in the wild.

What is the CISA deadline for CVE-2023-49105?

US federal agencies must remediate it by 30 August 2026. Everyone else should treat that date as the latest safe point to patch an internet-facing system.

How likely is CVE-2023-49105 to be exploited in the next 30 days?

FIRST's Exploit Prediction Scoring System gives it 43%, the 98th percentile of every CVE it scores.

How do I fix CVE-2023-49105?

Apply the vendor fix and restart the affected service. Put the login or management interface behind a VPN or allow-list; a bypass makes passwords irrelevant. Rotate credentials and session keys the product holds, and review accounts and configuration changes since the listing date.

Sources: CISA Known Exploited Vulnerabilities catalogue (released 10 November 2026) and FIRST EPSS. Page compiled automatically by SAK T.L.M, the threat-intelligence tool of SAK T.E.C, on 13 November 2026.