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Not in CISA KEV
MEDIUM severity

CVE-2021-3427 — deluge

MEDIUM

CVE-2021-3427 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in deluge. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for deluge — see the affected versions and patch details below.

Deluge Web-UI vulnerable to XSS through a crafted torrent file

Also known asGHSA-5c8p-qhch-qhx6PYSEC-2022-256
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
2 known
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.0%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs62th percentile — riskier than 62% of all scored CVEsHighest risk
0.13%0.57%1.02%1.46%0.6%1.0%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍deluge

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

The Deluge Web-UI is vulnerable to cross-site scripting through a crafted torrent file. The the data from torrent files is not properly sanitised as it's interpreted directly as HTML. Someone who supplies the user with a malicious torrent file can execute arbitrary Javascript code in the context of the user's browser session.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIdelugeall versions2.1.0pip install --upgrade 'deluge==2.1.0'

Affected Products

1 product · 1 configurations
Application
delugedeluge-torrent
< 2.1.0
range
Exploits & PoCs
2

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The Deluge Web-UI is vulnerable to XSS through a crafted torrent file. T…

groups.google.comNVDAug 2022

Report on dev.deluge-torrent.org

dev.deluge-torrent.orgNVDAug 2022

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for deluge, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update deluge to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3427 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

The Deluge Web-UI is vulnerable to cross-site scripting through a crafted torrent file. The the data from torrent files is not properly sanitised as it's interpreted directly as HTML. Someone who supplies the user with a malicious torrent file can execute arbitrary Javascript code in the context of the user's browser session.
O3 Security · Impact-Aware SCA

Is CVE-2021-3427 in your dependencies?

Find it across PyPI, including transitive dependencies.

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CVE-2021-3427: deluge XSS — Fixed in 2.1.0