---
id: CVE-2026-116748
title: Transmission 4.0.0 before 4.1.3 Permissive CORS Leaks RPC Anti-CSRF Token
summary: >-
  Transmission 4.0.0 before 4.1.3 contains a permissive CORS vulnerability in
  handle_request() in rpc-server.cc that exposes the X-Transmission-Session-Id
  anti-CSRF token to any web origin. Malicious web pages can read the token from
  the 4…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-942
vendor: transmission
product: transmission
affected:
  - transmission >= 4.0.0 < 4.1.3
published: '2026-10-26'
updated: '2026-10-26'
sourceUpdated: '2026-10-26T21:52:45.799Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-116748'
references:
  - url: 'https://github.com/transmission/transmission/pull/8938'
    label: 'Pull Request #8938'
  - url: >-
      https://github.com/transmission/transmission/commit/c6a1bd2017a0fea9c956737c213f23e4b0f7929e
    label: Patch Commit
  - url: 'https://github.com/transmission/transmission'
  - url: 'https://github.com/transmission/transmission/releases/tag/4.1.3'
    label: transmission 4.1.3 Release Notes
  - url: >-
      https://github.com/transmission/transmission/blob/4.1.2/libtransmission/rpc-server.cc#L560
  - url: 'https://joshua.hu/transmission-cors-rpc-csrf-rce-drive-by-exploit'
  - url: >-
      https://www.vulncheck.com/advisories/transmission-4.0.0-before-4.1.3-permissive-cors-leaks-rpc-anti-csrf-token
    label: >-
      VulnCheck Advisory: Transmission 4.0.0 before 4.1.3 Permissive CORS Leaks
      RPC Anti-CSRF Token
tags:
  - cve.org
epss: 0.00527
epssPercentile: 0.44465
ingestedAt: '2026-10-27T16:11:59.129Z'
---

## Overview

Transmission 4.0.0 before 4.1.3 contains a permissive CORS vulnerability in handle_request() in rpc-server.cc that exposes the X-Transmission-Session-Id anti-CSRF token to any web origin. Malicious web pages can read the token from the 409 handshake response and replay it to issue RPC calls, enabling script-torrent-done execution, download-dir changes, or torrent and data deletion.

## Affected

- `transmission >= 4.0.0 < 4.1.3`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.