Vulnerability in Transmission
CVE-2026-116748
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.
Published .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/transmission/transmission/pull/8938 (issue-tracking, patch)
- github.com/transmission/transmission/commit/c6a1bd2017a0fea9c956737c213f23e4b0f… (patch)
- github.com/transmission/transmission (product)
- github.com/transmission/transmission/releases/tag/4.1.3 (release-notes)
- github.com/transmission/transmission/blob/4.1.2/libtransmission/rpc-server.cc (technical-description)
- joshua.hu/transmission-cors-rpc-csrf-rce-drive-by-exploit (third-party-advisory)
- www.vulncheck.com/advisories/transmission-4.0.0-before-4.1.3-permissive-cors-le… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-116748?
- CVE-2026-116748 is a high-severity vulnerability in Transmission, classified under Permissive Cross-domain Policy with Untrusted Domains. CVSS score: 8.8/10. Published 2026-10-26.
- How severe is CVE-2026-116748?
- High severity. CVSS v3 base score is 8.8 out of 10.