External risk intelligence

Baileys WhatsApp API Spoofs Messages and Corrupts Sync

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-48063

Baileys is a library used to build applications that interact with the WhatsApp Web interface. These applications typically function as internet-facing API services or integrations that must remain reachable to process incoming messages and events from the WhatsApp network, making the attack surface commonly internet-exposed.

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability has been identified in the Baileys API for WhatsApp Web that could allow for message spoofing and manipulation of chat synchronization. This issue arises from the ability to send a specially crafted malicious payload, enabling an attacker to inject fake messages into conversations and disrupt the integrity of message history and app state. The risk is that the authenticity and completeness of communication logs could be compromised.

Spoofed messages can appear in conversations.
Integrity of chat history and sync is at risk.
Confirm if this API is used in your environment.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending a specially crafted message to a Baileys-enabled application. This message targets a specific function within the API, allowing the attacker to inject malicious data. This could lead to the spoofing of messages, corruption of application state, or the falsification of message history.

No special access required.
Triggered by sending a malicious message.
Enables message spoofing and state corruption.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to spoof messages and corrupt the app state sync and history sync systems by sending malicious payloads. When supported by the advisory, this could impact the integrity of message history and user-provided context within the application.

WhatsApp message integrity and history.
Malicious payloads can be sent via API.
Spoofed messages and corrupted app state.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Baileys library's exploitation of message spoofing and state synchronization corruption indicates that application owners or platform teams responsible for services utilizing this API should take immediate action. The initial step involves identifying all deployments of Baileys, assessing their exposure to external networks, and confirming their business criticality to prioritize remediation efforts.

Own the issue and coordinate fixes.
Verify affected deployments and their criticality.
Plan remediation based on risk assessment.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is Baileys?

Baileys is an open-source library built on TypeScript and JavaScript that allows developers to create custom API services for WhatsApp Web. It acts as an interface between your application code and the WhatsApp network, enabling automated tasks like sending messages or managing chat sessions. Engineers use it to build chatbots, customer support integrations, or notification systems that need to interact programmatically with WhatsApp messaging features.

What is the vulnerability in CVE-2026-48063?

This vulnerability involves improper authentication and message integrity failures, classified as CWE-290, CWE-345, and CWE-346. Essentially, the software fails to verify the authenticity of incoming payloads. By sending a malicious message to a specific API function, an attacker can trick the system into accepting fake data as legitimate, leading to message spoofing and corruption of the application's internal sync state.

How can an attacker trigger this bug?

An attacker triggers this issue by sending a specially crafted payload to the placeholderResendMessage function within the library. This action tricks the system into executing a fake message.upsert event. It is important to note that the attacker does not need special administrative privileges or internal network access; the exploit relies entirely on the library's mishandling of incoming message data, not on circumventing existing login credentials.

Is my Baileys integration at risk?

Because Baileys is designed to process incoming messages from the WhatsApp network, Halo Surface Signal notes that applications using it are typically internet-facing API services. If your service must remain reachable to receive external events, it is inherently exposed. You should evaluate if your application is internet-accessible and actively processing external traffic, as these factors increase the likelihood of this vulnerability being reached by an attacker.

How do I fix CVE-2026-48063?

Your first step is to inventory all services currently running the Baileys library to identify affected versions. If your environment is running anything earlier than version 6.7.22 or 7.0.0-rc12, you are vulnerable. Prioritize updating these dependencies to the patched versions immediately. Once updated, verify that the integration maintains its expected functionality while ensuring that security controls for your API endpoints remain active.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.