Summary
malicious SVG attachment causing stored XSS vulnerability
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
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.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2020-15275 has a CVSS score of 8.7 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.9.11); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
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.
Frequently Asked Questions
- What is CVE-2020-15275? CVE-2020-15275 is a medium-severity cross-site scripting (XSS) vulnerability in moin (pip), affecting versions < 1.9.11. It is fixed in 1.9.11. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2020-15275? CVE-2020-15275 has a CVSS score of 8.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of moin are affected by CVE-2020-15275? moin (pip) versions < 1.9.11 is affected.
- Is there a fix for CVE-2020-15275? Yes. CVE-2020-15275 is fixed in 1.9.11. Upgrade to this version or later.
- Is CVE-2020-15275 exploitable, and should I be worried? Whether CVE-2020-15275 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-15275 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-15275? Upgrade
mointo 1.9.11 or later.