VDB-339985 · CVE-2026-21857 · GHSA-824x-88xg-cwrv

REDAXO up to 5.20.1 Backup EXPDIR path traversal

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5.5	$0-$5k	0.00

Summaryinfo

A vulnerability identified as problematic has been detected in REDAXO up to 5.20.1. This affects an unknown function of the component Backup Handler. This manipulation of the argument EXPDIR causes path traversal. This vulnerability is registered as CVE-2026-21857. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in REDAXO up to 5.20.1. Affected by this vulnerability is some unknown functionality of the component Backup Handler. The manipulation of the argument EXPDIR with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-24. The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize "../" sequences that can resolve to a location that is outside of that directory. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-21857 since 01/05/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation requires an enhanced level of successful authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 5.20.2 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-0817). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

REDAXO

Version

Website

Product: https://github.com/redaxo/redaxo/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 4.7
VulDB Temp Score: 4.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.5
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Path traversal
CWE: CWE-24 / CWE-23 / CWE-22
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: REDAXO 5.20.2

Timelineinfo

01/05/2026 CVE reserved
01/08/2026 +3 days Advisory disclosed
01/08/2026 +0 days VulDB entry created
01/21/2026 +13 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-824x-88xg-cwrv
Status: Confirmed

CVE: CVE-2026-21857 (🔒)
GCVE (CVE): GCVE-0-2026-21857
GCVE (VulDB): GCVE-100-339985
EUVD: 🔒

Entryinfo

Created: 01/08/2026 07:46
Updated: 01/21/2026 04:21
Changes: 01/08/2026 07:46 (68), 01/08/2026 11:55 (1), 01/21/2026 04:21 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.