CVE-2021-42576: Cross-site scripting in github.com/microcosm-cc/bluemonday
Summary
CVE-2021-42576: Cross-site scripting in github.com/microcosm-cc/bluemonday. Affects github.com/microcosm-cc/bluemonday versions < 1.0.16. Fixed in 1.0.16. How to fix ↓
Also tracked for
- pybluemonday · PyPI
- golang-github-microcosm-cc-bluemonday · Debian:11
- pybluemonday · PyPI
The same CVE-2021-42576 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
The package under scrutiny is github.com/microcosm-cc/bluemonday, an HTML sanitizer for Go. It is designed to prevent cross-site scripting (XSS) attacks by sanitizing HTML input. The package provides various policies to customize the allowed HTML elements and attributes. However, user-defined policies allowing 'select', 'style', and 'option' elements are vulnerable to a cross-site scripting vulnerability.
Vulnerability Detail
The bluemonday HTML sanitizer can leak the contents of a 'style' element into HTML output, potentially causing XSS vulnerabilities. This vulnerability affects user-defined policies that allow 'select', 'style', and 'option' elements. The default bluemonday sanitization policies are not vulnerable. It is important to note that permitting the 'style' element in policies is hazardous because bluemonday does not contain a CSS sanitizer. Newer versions of bluemonday suppress 'style' and 'script' elements even when allowed by a policy unless the policy explicitly requests unsafe processing.
How To Fix
Minimum fixed version
1.0.16
This is the first release that contains the fix.
go get github.com/microcosm-cc/bluemonday@v1.0.16Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There is no specific workaround mentioned for this vulnerability. It is advised to update the package to the fixed version.
Conclusion
In conclusion, the package github.com/microcosm-cc/bluemonday is vulnerable to a cross-site scripting (XSS) vulnerability when user-defined policies allow 'select', 'style', and 'option' elements. It is recommended to update the package to version 1.0.16 or later to fix this vulnerability. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for github.com/microcosm-cc/bluemonday →
FAQ
Bluemonday is an HTML sanitizer for Go that helps prevent cross-site scripting (XSS) attacks by sanitizing HTML input.
Versions prior to 1.0.16 are affected by this vulnerability.
No, the default bluemonday sanitization policies are not vulnerable to this XSS vulnerability.
This vulnerability can lead to cross-site scripting (XSS) attacks, potentially allowing an attacker to execute malicious scripts on the affected website.
No, bluemonday does not contain a CSS sanitizer. It is hazardous to permit the 'style' element in policies.
References
Related vulnerabilities
Recent vulnerabilities recorded for github.com/microcosm-cc/bluemonday.
