Path Traversal Vulnerability in REDAXO CMS Backup Addon
CVE-2026-21857

8.3HIGH

Key Information:

Vendor

Redaxo

Status
Redaxo
Vendor
CVE Published:
7 January 2026

What is CVE-2026-21857?

The REDAXO CMS has a path traversal vulnerability in the Backup addon, allowing authenticated users with backup permissions to read sensitive files within the webroot. This issue arises from inadequate validation of the EXPDIR POST parameter, enabling attackers to exploit relative paths (../) or specify absolute paths to create a .tar.gz archive containing arbitrary files. The vulnerability has been addressed in version 5.20.2, emphasizing the need for users to upgrade immediately to ensure their systems are secure.

Affected Version(s)

redaxo < 5.20.2

References

https://github.com/redaxo/redaxo/security/advisories/GHSA...
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https://github.com/redaxo/redaxo/releases/tag/5.20.2
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CVSS V4

Score:
8.3
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.