External risk intelligence

SillyTavern DNS Rebinding Vulnerability Allows Remote Code Execution and Data Theft.

CVE advisorySeverity: CRITICAL (CVSS 9.6)

CVE-2025-59159

SillyTavern is explicitly described as a locally installed user interface for interacting with local or remote language models. It is designed for individual user workstations and is not a network edge service, gateway, or public-facing web application. Exposure to the internet would be a non-standard, atypical configuration, as it is intended for local or restricted private network usage.

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the SillyTavern user interface could allow unauthorized access to user interactions and systems. This issue affects how the interface handles network requests and could potentially lead to the installation of malicious extensions or the injection of harmful content. The main concern is confirming relevance and exposure to this type of interface.

User interface may allow remote compromise.
Critical flaws could impact user data privacy.
Assess local interface use and configurations.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this by tricking a user into visiting a malicious website. This website would then interact with the vulnerable SillyTavern application, potentially allowing the attacker to install harmful extensions, steal chat data, or inject fake content.

Requires user interaction via a malicious website.
DNS rebinding on the web interface.
Arbitrary code execution and data theft.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory, the web interface of SillyTavern could be exploited through DNS rebinding to allow an attacker to perform malicious actions, such as reading user chats or injecting HTML for phishing. This could occur if the application is hosted over a local network without SSL and the host name validation is not properly configured.

User chats and sensitive information could be read.
Malicious extensions may be installed.
Arbitrary HTML injection for phishing is possible.

Operational Fix

Recommended remediation, mitigation, and detection steps

The primary responsibility for addressing this vulnerability likely falls to the user or system owner who installed and configured SillyTavern, as it's a locally installed application. The first practical step is to identify all instances of SillyTavern, assess their network exposure, and confirm the accountable owner. Subsequently, a plan for remediation should be developed based on the identified risks, considering configuration updates to mitigate the DNS rebinding vulnerability.

User/system owner must address.
Verify network reachability and exposure.
Configure host whitelisting for security.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is SillyTavern?

SillyTavern is a locally installed user interface designed to help individuals interact with text generation, image generation, and text-to-speech AI models. It acts as a bridge, allowing users to connect to various large language models to manage chats and media generation, typically on a personal workstation or a private local system.

How does DNS rebinding impact CVE-2025-59159?

This vulnerability involves DNS rebinding, which falls under the weakness classes of Improper Validation of Origin and Improper Neutralization of Input. It allows an attacker to bypass browser security policies by tricking the application into accepting requests from a malicious source, granting the attacker the ability to interact with the interface as if they were the legitimate user.

Do I need to be a specific target for this to trigger?

Yes. This attack requires a user to actively visit a malicious website while their local SillyTavern instance is running. Simply having the software installed is not enough; the attacker must manipulate the user's browser to send unexpected requests to the interface. The bug is not triggered if you do not browse the web while the application is active.

Is my SillyTavern instance relevant to this threat?

Halo Surface Signal notes that SillyTavern is designed for individual workstations, making internet-facing exposure atypical. If your setup is strictly local and you do not expose the interface to the internet or wide local networks without SSL, your risk is significantly lower. Evaluate if your configuration makes the interface reachable by external or untrusted network traffic.

What steps should I take to secure my installation?

First, update to version 1.13.4 or later. Next, enable host whitelisting by modifying your config.yaml file or using the SILLYTAVERN_HOSTWHITELIST_ENABLED environment variable. This feature validates inbound HTTP requests against a list of allowed hosts, which directly prevents unauthorized entities from rebinding to your local interface.

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.