How severe is CVE-2020-15275?

CVE-2020-15275 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-15275?

CVE-2020-15275 affects the following packages: moin (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2020-15275?

Update moin to 1.9.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15275 is resolved across your whole dependency graph.

How do I detect CVE-2020-15275 in my PyPI dependencies?

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

How do I mitigate CVE-2020-15275 if there is no patch (or I can't update yet)?

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.

Is CVE-2020-15275 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2020-15275, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-15275?

CVE-2020-15275 has an EPSS (Exploit Prediction Scoring System) score of 1.7%, placing it in the 77th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-15275?

CVE-2020-15275 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2020-15275 published, and has it been updated?

CVE-2020-15275 was published on November 11, 2020 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2020-15275 — moin

MEDIUMFix: moinwiki/moin-1.9@31de913

CVE-2020-15275 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in moin. 1 public exploit reference exists, so weaponization risk is real. A fix is available for moin — see the affected versions and patch details below.

malicious SVG attachment causing stored XSS vulnerability

Also known asGHSA-4q96-6xhq-ff43PYSEC-2020-241

Published

Nov 11, 2020

Updated

Jul 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Oct 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs77th percentile — riskier than 77% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2020-15275 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

🐍moin

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

Impact

An attacker with write permissions can upload an SVG file that contains malicious javascript. This javascript will be executed in a user's browser when the user is viewing that SVG file on the wiki.

Patches

Users are strongly advised to upgrade to a patched version.

MoinMoin Wiki 1.9.11 has the necessary fixes and also contains other important fixes.

Workarounds

It is not advised to work around this, but to upgrade MoinMoin to a patched version.

That said, a work around via a Content Security Policy in the web server might be possible.

Also, it is of course helpful if you give write permissions (which include uploading attachments) only to trusted users.

For more information

If you have any questions or comments about this advisory, email me at [email protected].

Credits

This vulnerability was discovered by:

Catarina Leite from the Checkmarx SCA AppSec team

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`moin`	all versions	1.9.11`pip install --upgrade 'moin==1.9.11'`

Affected Products

1 product · 1 configurations

Application

moinmoinmoinmo

< 1.9.11

range

Exploits & PoCs

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

MoinMoin is a wiki engine. In MoinMoin before version 1.9.11, an attacke…

advisory.checkmarx.netNVDOct 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for moin, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update moin to 1.9.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15275 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

### Impact An attacker with `write` permissions can upload an SVG file that contains malicious javascript. This javascript will be executed in a user's browser when the user is viewing that SVG file on the wiki. ### Patches Users are strongly advised to upgrade to a patched version. MoinMoin Wiki 1.9.11 has the necessary fixes and also contains other important fixes. ### Workarounds It is not advised to work around this, but to upgrade MoinMoin to a patched version. That said, a work around via a Content Security Policy in the web server might be possible. Also, it is of course helpful if