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Actively exploitedCVSS 9.8 · CRITICAL

CVE-2023-49105Authentication bypass in ownCloud core

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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Analysis

Esta vulnerabilidad crítica en ownCloud permite a atacantes remotos acceder, modificar o eliminar archivos sin autenticación si conocen el nombre de usuario de la víctima. El fallo se debe a la aceptación incorrecta de URLs prefirmadas y está siendo explotado activamente en entornos reales. Es indispensable actualizar las instancias de ownCloud core a la versión 10.13.1 o superior de inmediato.

Relevant roles

PhpBackendCloudLinuxciberseguridad

Severity

Score: 9.8(CRITICAL)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AV: NETWORK
AC: LOW
PR: NONE
UI: NONE
S: UNCHANGED
C: HIGH
I: HIGH
A: HIGH
Weakness (CWE): CWE-287

CISA KEV

Added to KEV: 2026-08-27
Federal patch deadline: 2026-08-30
Known ransomware use: Unknown
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.

EPSS

Probability of exploitation (next 30 days): 0.1107 (11.1%)
Percentile: 95.6%
EPSS: 2026-08-27

Affects

owncloud:owncloud_server

Technical description

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.

Published: 11/21/2023, 10:15:08 PM
Last modified: 6/17/2026, 6:35:22 AM

References

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