Vulnerability-Lookup

CVE-2026-44651 (GCVE-0-2026-44651)

Vulnerability from cvelistv5 – Published: 2026-05-29 17:49 – Updated: 2026-06-01 15:20

Title

SillyTavern: Reflected XSS vulnerability in the CORS proxy middleware

Summary

SillyTavern is a locally installed user interface that allows users to interact with text generation large language models, image generation engines, and text-to-speech voice models. Prior to 1.18.0, when fetch(url) throws, the code sends: res.status(500).send('Error occurred while trying to proxy to: ' + url + ' ' + error). The url value is attacker-controlled (req.params.url) and is not HTML-escaped before rendering. This vulnerability is fixed in 1.18.0.

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-01 15:20 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/SillyTavern/SillyTavern/securi…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
SillyTavern	SillyTavern	Affected: < 1.18.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-44651

Vulnerability from fkie_nvd - Published: 2026-05-29 19:16 - Updated: 2026-07-22 06:10

Severity

6.9 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/SillyTavern/SillyTavern/security/advisories/GHSA-xc4x-2452-5gc9

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "SillyTavern",
          "vendor": "SillyTavern",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.18.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
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    {
      "lang": "en",
      "value": "SillyTavern is a locally installed user interface that allows users to interact with text generation large language models, image generation engines, and text-to-speech voice models. Prior to 1.18.0, when fetch(url) throws, the code sends:\nres.status(500).send(\u0027Error occurred while trying to proxy to: \u0027 + url + \u0027 \u0027 + error). The url value is attacker-controlled (req.params.url) and is not HTML-escaped before rendering. This vulnerability is fixed in 1.18.0."
    },
    {
      "lang": "es",
      "value": "SillyTavern es una interfaz de usuario instalada localmente que permite a los usuarios interactuar con modelos de lenguaje grandes de generaci\u00f3n de texto, motores de generaci\u00f3n de im\u00e1genes y modelos de voz de texto a voz. Antes de la 1.18.0, cuando fetch(url) lanza un error, el c\u00f3digo env\u00eda: res.status(500).send(\u0027Ocurri\u00f3 un error al intentar hacer proxy a: \u0027 + url + \u0027 \u0027 + error). El valor de la url es controlado por el atacante (req.params.url) y no se escapa en HTML antes de renderizar. Esta vulnerabilidad se corrige en la 1.18.0."
    }
  ],
  "id": "CVE-2026-44651",
  "lastModified": "2026-07-22T06:10:00.170",
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          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.9,
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GHSA-XC4X-2452-5GC9

Vulnerability from github – Published: 2026-05-12 22:23 – Updated: 2026-06-09 10:32

Summary

SillyTavern has a reflected XSS vulnerability in the CORS proxy middleware

Details

Resolution

Fixed in SillyTavern 1.18.0: a user-provided URL is no longer reflected in the HTTP response body.

Overview

Vulnerability Type: XSS
Affected Location: src/middleware/corsProxy.js:40
Trigger Scenario: reflected XSS in CORS proxy error response

Root Cause

When fetch(url) throws, the code sends: res.status(500).send('Error occurred while trying to proxy to: ' + url + ' ' + error). The url value is attacker-controlled (req.params.url) and is not HTML-escaped before rendering.

Source-to-Sink Chain

Source (user-controlled input)
Entry point: GET /proxy/:url(*)
Data flow
Code analysis shows concrete propagation into this sink:
vulnerability title: Reflected XSS in CORS proxy error response
sink location reached by attacker-controlled input: src/middleware/corsProxy.js:40
The same sink behavior is confirmed by controlled execution observations.
Sink (dangerous operation)
Sink location: src/middleware/corsProxy.js:40
Vulnerable behavior: reflected XSS in CORS proxy error response

Exploitation Preconditions

The attacker can inject controllable content into a rendered response.
The vulnerable rendering context does not apply strict output encoding/sanitization.
A victim user opens the affected page or response.

Risk

This issue enables script execution in the victim context and can compromise session or data integrity.

Impact

An attacker may run arbitrary JavaScript in the victim context, steal tokens, and manipulate user-visible behavior.

Remediation

Never concatenate raw user input into HTML error responses.
If URL echo is required, HTML-escape it or force plain-text output.
Re-enable/strengthen CSP to reduce reflected injection impact.

Severity

6.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.17.0"
      },
      "package": {
        "ecosystem": "npm",
        "name": "sillytavern"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.18.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44651"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-12T22:23:56Z",
    "nvd_published_at": "2026-05-29T19:16:24Z",
    "severity": "MODERATE"
  },
  "details": "## Resolution\n\nFixed in SillyTavern 1.18.0: a user-provided URL is no longer reflected in the HTTP response body.\n\n## Overview\n- Vulnerability Type: XSS\n- Affected Location: `src/middleware/corsProxy.js:40`\n- Trigger Scenario: reflected XSS in CORS proxy error response\n\n## Root Cause\nWhen `fetch(url)` throws, the code sends:\n`res.status(500).send(\u0027Error occurred while trying to proxy to: \u0027 + url + \u0027 \u0027 + error)`.\nThe `url` value is attacker-controlled (`req.params.url`) and is not HTML-escaped before rendering.\n\n## Source-to-Sink Chain\n1. Source (user-controlled input)\n- Entry point: `GET /proxy/:url(*)`\n\n2. Data flow\n- Code analysis shows concrete propagation into this sink:\n  - vulnerability title: `Reflected XSS in CORS proxy error response`\n  - sink location reached by attacker-controlled input: `src/middleware/corsProxy.js:40`\n- The same sink behavior is confirmed by controlled execution observations.\n\n3. Sink (dangerous operation)\n- Sink location: `src/middleware/corsProxy.js:40`\n- Vulnerable behavior: reflected XSS in CORS proxy error response\n\n## Exploitation Preconditions\n1. The attacker can inject controllable content into a rendered response.\n2. The vulnerable rendering context does not apply strict output encoding/sanitization.\n3. A victim user opens the affected page or response.\n\n## Risk\nThis issue enables script execution in the victim context and can compromise session or data integrity.\n\n## Impact\nAn attacker may run arbitrary JavaScript in the victim context, steal tokens, and manipulate user-visible behavior.\n\n## Remediation\n1. Never concatenate raw user input into HTML error responses.\n2. If URL echo is required, HTML-escape it or force plain-text output.\n3. Re-enable/strengthen CSP to reduce reflected injection impact.",
  "id": "GHSA-xc4x-2452-5gc9",
  "modified": "2026-06-09T10:32:13Z",
  "published": "2026-05-12T22:23:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/SillyTavern/SillyTavern/security/advisories/GHSA-xc4x-2452-5gc9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44651"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/SillyTavern/SillyTavern"
    },
    {
      "type": "WEB",
      "url": "https://github.com/SillyTavern/SillyTavern/releases/tag/1.18.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "SillyTavern has a reflected XSS vulnerability in the CORS proxy middleware"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-44651 (GCVE-0-2026-44651)

FKIE_CVE-2026-44651

GHSA-XC4X-2452-5GC9

Resolution

Overview

Root Cause

Source-to-Sink Chain

Exploitation Preconditions

Risk

Impact

Remediation

Tags

Sightings

Nomenclature

Related by attack behaviour