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.
References7
- github.com/transmission/transmission
- github.com/transmission/transmission/blob/4.1.2/libtransmission…
- github.com/transmission/transmission/commit/c6a1bd2017a0fea9c95…
- github.com/transmission/transmission/pull/8938
- github.com/transmission/transmission/releases/tag/4.1.3
- joshua.hu/transmission-cors-rpc-csrf-rce-drive-by-exploit
- www.vulncheck.com/advisories/transmission-4.0.0-before-4.1.3-pe…
Metrics
- CVSS 3.1
-
8.8
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H - CVSS 4.0
-
8.7
HIGH
Score source: CNA
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 69 · as of 8 November 2026
- CWE
- CWE-942
Could this be exploited in your environment?
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