What is the CVSS score of CVE-2026-21857?

CVE-2026-21857 has a CVSS 3.1 base score of 6.5 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N. EPSS exploitation probability: 0.0%.

Which versions of PHP are affected by CVE-2026-21857?

Organizations using REDAXO should be aware of notable risk from CVE-2026-21857, a path traversal vulnerability rated CVSS 6.5. This could allow unauthorized file access.. A patch is available.

Is there a public PoC exploit available for CVE-2026-21857?

Yes, a public proof-of-concept exploit is available for CVE-2026-21857. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-21857?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Review file handling controls.

PHP CVE-2026-21857

MEDIUM

Path Traversal (CWE-22)

2026-01-07 security-advisories@github.com

GHSA-824x-88xg-cwrv

PHP Path Traversal Redaxo

6.5

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

6.5 MEDIUM

AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Jan 20, 2026 - 18:49 vuln.today

Public exploit code

CVE Published

Jan 07, 2026 - 23:15 nvd

MEDIUM 6.5

DescriptionGitHub Advisory

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.

AnalysisAI

Arbitrary file disclosure in REDAXO's Backup addon allows authenticated users with backup permissions to read any file within the webroot by bypassing directory validation in the file export function. An attacker can manipulate the EXPDIR parameter with path traversal sequences to include unauthorized files in exported archives. Public exploit code exists; a patch is available in version 5.20.2 and later.

Technical ContextAI

Classified as CWE-22 (Path Traversal). Affects Redaxo. 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

RemediationAI

Monitor vendor advisories for a patch. Validate and sanitize file path inputs. Use allowlists. Restrict network access to the affected service where possible.