# CVE-2026-116748: Transmission 4.0.0 before 4.1.3 Permissive CORS Leaks RPC Anti-CSRF Token


- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 26 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-116748, GHSA-jw4h-7968-5hj9, UBUNTU-CVE-2026-116748

## What is CVE-2026-116748?

CVE-2026-116748 is a high-severity vulnerability in transmission, published on 26 Oct 2026. 

### Official 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.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains)

## Which versions are affected by CVE-2026-116748?


## How do I fix CVE-2026-116748?

Upgrade to a fixed version.

## Is CVE-2026-116748 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-116748 exists.

Public exploit code:

- Transmission 4.0.0-4.1.2 - Permissive CORS Exposes RPC Session ID (nuclei): http/cves/2026/CVE-2026-116748.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-116748 and fix it if it is affected.

What it is: CVE-2026-116748 is a high-severity vulnerability in transmission, published on 26 Oct 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-116748 exists.

Affected product: transmission. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-116748/ (Markdown: https://insights.sbomify.com/CVE-2026-116748/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-116748
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-116748
- OSV: https://osv.dev/vulnerability/CVE-2026-116748

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-116748/
Summaries are generated and may contain mistakes; the official description above is the record.