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MEDIUM severity

CVE-2021-3780 — peertube

MEDIUMFix: chocobozzz/peertube@0ea2f79

CVE-2021-3780 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in peertube. 1 public exploit reference exists, so weaponization risk is real. A fix is available for peertube — see the affected versions and patch details below.

Cross-site Scripting in peertube

Also known asGHSA-f2c5-997w-7f5c
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs58th percentile — riskier than 58% of all scored CVEsHighest risk
0.00%0.47%0.93%1.40%0.3%0.9%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-3780 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

0other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
peertubenpm
8downloads / week

Description

peertube is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). It was found that one could upload a SVG image and then send the url of that to other users and when they open the link we can get their complete session keys as the session keys stored in local storage and with Javascript easily can be stolen by attackers.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmpeertubeall versions3.4.0npm install peertube@3.4.0

Affected Products

1 product · 1 configurations
Application
peertubeframasoft
< 3.4.0
range
Exploits & PoCs
1

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

peertube is vulnerable to Improper Neutralization of Input During Web Pa…

huntr.devNVDSep 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update peertube to 3.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3780 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

peertube is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). It was found that one could upload a SVG image and then send the url of that to other users and when they open the link we can get their complete session keys as the session keys stored in local storage and with Javascript easily can be stolen by attackers.
O3 Security · Impact-Aware SCA

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CVE-2021-3780: peertube XSS — Fixed in 3.4.0