CVE-2026-116748 (CVSS 8.8)

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.

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CVSS v3.1 Score

8.8

HIGH

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

EPSS — Exploit Prediction

0.0125

Probability of exploitation

0.70%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-942 CWE-942

References

Other References

https://github.com/transmission/transmission https://github.com/transmission/transmission/blob/4.1.2/libtransmission/rpc-server.cc#L560 https://github.com/transmission/transmission/commit/c6a1bd2017a0fea9c956737c213f23e4b0f7929e https://github.com/transmission/transmission/pull/8938 https://github.com/transmission/transmission/releases/tag/4.1.3 https://joshua.hu/transmission-cors-rpc-csrf-rce-drive-by-exploit https://www.vulncheck.com/advisories/transmission-4.0.0-before-4.1.3-permissive-cors-leaks-rpc-anti-csrf-token

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-116748? +

CVE-2026-116748 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0125, placing it in the 1th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-116748? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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