CVE-2021-25963 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in shuup. A fix is available for shuup — see the affected versions and patch details below.
Cross-site Scripting in shuup
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-25963.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-25963 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
shuupReal-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
In Shuup, versions 1.6.0 through 2.10.8 are vulnerable to reflected Cross-Site Scripting (XSS) that allows execution of arbitrary javascript code on a victim browser. This vulnerability exists due to the error page contents not escaped.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | shuup | ≥ 1.6.0&&< 2.11.0 | 2.11.0pip install --upgrade 'shuup==2.11.0' |
Affected Products
shuupshuupDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for shuup, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update shuup to 2.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-25963 is resolved across your whole dependency graph.
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
Is CVE-2021-25963 in your dependencies?
Find it across PyPI, including transitive dependencies.