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Vulnerabilities

Vulnerability · CVE-2026-21857

REDAXO is a PHP-based content management system.

Published Jan 7, 2026 · catalog updated Jan 8, 2026 · Redaxo

Last checked Nov 3, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-21857. EPSS is 0.53%. Act only if a listed version of Redaxo is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High8.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.53%
Remediation
Version ranges on file
Affected products
vendor Redaxo redaxo < 5.20.2

REDAXO is a PHP-based content management system. Prior to version 5.20.2, authenticated users with backup permissions can read arbitrary files within the webroot via path traversal in the Backup addon's file export functionality. The Backup addon does not validate the POST parameter against the UI-generated allowlist of permitted directories. An attacker can supply relative paths containing sequences (or even absolute paths inside the document root) to include any readable file in the generated archive. Version 5.20.2 fixes this issue.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Redaxo redaxo < 5.20.2< 5.20.2

How to fix CVE-2026-21857

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-21857. EPSS is 0.53%. Act only if a listed version of Redaxo is installed.

Which versions are affected?

Compare what you have installed with Redaxo redaxo < 5.20.2 < 5.20.2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.53%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jan 7, 2026 · EUVD

    Detected

    REDAXO is a PHP-based content management system. Prior to version 5.20.2, authenticated users with backup permissions can read arbitrary files within the webroot via path traversal in the Backup addon's file export functionality. The Backup addon does not validate the POST parameter against the UI-generated allowlist of permitted directories. An attacker can supply relative paths containing sequen

  2. Jan 8, 2026 · EUVD

    Updated

    REDAXO is a PHP-based content management system. Prior to version 5.20.2, authenticated users with backup permissions can read arbitrary files within the webroot via path traversal in the Backup addon's file export functionality. The Backup addon does not validate the POST parameter against the UI-generated allowlist of permitted directories. An attacker can supply relative paths containing sequen

Sources

  • CVE.orgVulnerability recordCVE-2026-21857

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-21857

    30-day exploitation probability 0.53%

    first.org
  • EUVDVulnerability recordEUVD-2026-0817

    REDAXO is a PHP-based content management system. Prior to version 5.20.2, authenticated users with backup permissions can read arbitrary files within the webroot via path traversal in the Backup addon's file export functionality. The Backup addon does not validate the POST parame

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 3, 2026
  • CVE.orgOct 31, 2026
  • EUVDOct 30, 2026