CVE-2013-4338

WordPress Core < 3.6.1 - Deserialization

2013-09-11 00:00

Strategic Overview

Status: Patched in 3.6.1
Affected Core: WordPress 3.6
Affected Version: <= 3.6
CVSS: 8.8High
Weakness type: CWE-502 · Deserialization of Untrusted Data
CVE: CVE-2013-4338

At a glance

CVE-2013-4338 is a high-severity Deserialization of Untrusted Data vulnerability in the WordPress 3.6 WordPress release line, affecting <= 3.6. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). The issue is fixed in version 3.6.1; sites on affected versions should update now. Disclosed September 2013, reported by Tom Van Goethem.

Vulnerability Overview

wp-includes/functions.php in WordPress before 3.6.1 does not properly determine whether data has been serialized, which allows remote attackers to execute arbitrary code by triggering erroneous PHP unserialize operations.

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, integrity, availability — full site compromise territory.

CWE-502: Deserialization of Untrusted Data

Reaching this weakness in WordPress 3.6 <= 3.6 takes a caller who can reach the endpoint. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.

A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. For WordPress 3.6 the fix is 3.6.1: builds <= 3.6 are affected, anything from 3.6.1 onward is not.

Remediation

Update to version 3.6.1, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to WordPress 3.6: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: updating to 3.6.1 is the step that ends it.

Firewall
Scanner
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2013-4338 https://www.wordfence.com/threat-intel/vulnerabilities/id/d91ea0c9-ee41-4c8f-a16b-8b36c7f0a72e https://nvd.nist.gov/vuln/detail/CVE-2013-4338

Related records

Same weakness class

Other vulnerabilities in WordPress 3.6

CVSS Vector

8.8

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredLow
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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