How severe is CVE-2026-21857?

CVE-2026-21857 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-21857 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (39th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21857?

CVE-2026-21857 affects Redaxo. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21857?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-21857 have an EU (EUVD) identifier?

Yes. CVE-2026-21857 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-0817.

When was CVE-2026-21857 published?

CVE-2026-21857 was published on 2026-01-07 and last updated on 2026-06-17.

CVE-2026-21857

CVE-2026-21857 is a medium-severity vulnerability in Redaxo with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 8.3
EPSS exploit prediction: 0% (39th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-0817
Weakness: CWE-22
Affected product: Redaxo
Published: 2026-01-07
Last modified: 2026-06-17

Description

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 `EXPDIR` 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 `.tar.gz` archive. Version 5.20.2 fixes this issue.

Frequently asked questions

What is CVE-2026-21857?: 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 `EXPDIR` 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 `.tar.gz` archive. Version 5.20.2 fixes this issue.
How severe is CVE-2026-21857?: CVE-2026-21857 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-21857 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (39th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21857?: CVE-2026-21857 affects Redaxo. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21857?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21857 have an EU (EUVD) identifier?: Yes. CVE-2026-21857 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-0817.
When was CVE-2026-21857 published?: CVE-2026-21857 was published on 2026-01-07 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:redaxo:redaxo:*:*:*:*:*:*:*:*

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