CVE-2026-116748

high

Description

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.

References

https://www.vulncheck.com/advisories/transmission-4.0.0-before-4.1.3-permissive-cors-leaks-rpc-anti-csrf-token

https://joshua.hu/transmission-cors-rpc-csrf-rce-drive-by-exploit

https://github.com/transmission/transmission/releases/tag/4.1.3

https://github.com/transmission/transmission/pull/8938

https://github.com/transmission/transmission/commit/c6a1bd2017a0fea9c956737c213f23e4b0f7929e

https://github.com/transmission/transmission/blob/4.1.2/libtransmission/rpc-server.cc#L560

https://github.com/transmission/transmission

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-110496

Details

Source: Mitre, NVD

Published: 2026-10-26

Updated: 2026-10-27

Risk Information

CVSS v2

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

Severity: Critical

CVSS v3

Base Score: 8.8

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Severity: High

CVSS v4

Base Score: 8.7

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

Severity: High

EPSS

EPSS: 0.00527