CVE-2026-4853

JetBackup <= 3.1.19.8 - Authenticated (Administrator+) Arbitrary Directory Deletion via Path Traversal in 'fileName' Parameter

2026-04-16 15:21
lucsob

Strategic Overview

Status
Patched in 3.1.20.3
Affected Version
<= 3.1.19.8
CVSS
4.9Medium
Weakness type
CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CVE
CVE-2026-4853
View all JetBackup – Backup, Restore & Migrate vulnerabilities

At a glance

CVE-2026-4853 is a medium-severity Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in the JetBackup WordPress plugin, affecting versions <= 3.1.19.8. It carries a CVSS score of 4.9 (reachable over the network; low attack complexity; high confidentiality impact). Exploitation requires an authenticated account at Administrator level or above. The issue is fixed in version 3.1.20.3; sites on affected versions should update now. Disclosed April 2026, reported by lucsob.

Vulnerability Overview

The JetBackup – Backup, Restore & Migrate plugin for WordPress is vulnerable to Path Traversal leading to Arbitrary Directory Deletion in versions up to and including 3.1.19.8. This is due to insufficient input validation on the fileName parameter in the file upload handler. The plugin sanitizes the fileName parameter using sanitize_text_field(), which removes HTML tags but does not prevent path traversal sequences like '../'. The unsanitized filename is then directly concatenated in Upload::getFileLocation() without using basename() or validating the resolved path stays within the intended directory. When an invalid file is uploaded, the cleanup logic calls dirname() on the traversed path and passes it to Util::rm(), which recursively deletes the entire resolved directory. This makes it possible for authenticated attackers with administrator-level access to traverse outside the intended upload directory and trigger deletion of critical WordPress directories such as wp-content/plugins, effectively disabling all installed plugins and causing severe site disruption.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user. A successful exploit has high impact on confidentiality.

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

JetBackup <= 3.1.19.8 carries this weakness at sanitize_text_field(), and reaching it takes an account at Administrator level or above. Path traversal happens when user-controlled text is used to build a filesystem path without being constrained to an intended directory, so sequences like ../ walk the resolved path somewhere else.

Depending on the operation, it means reading files outside the intended folder — wp-config.php being the usual target — or writing to and deleting paths the web server can touch. For JetBackup the fix is 3.1.20.3: builds <= 3.1.19.8 are affected, anything from 3.1.20.3 onward is not.

Remediation

Update to version 3.1.20.3, or a newer patched version

How does WordSec protect against this?

An attacker needs Administrator access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: JetBackup 3.1.20.3 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

Related records

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