Описание
Cross-site Scripting in Sanitize
When HTML is sanitized using Sanitize's "relaxed" config or a custom config that allows certain elements, some content in a <math> or <svg> element may not be sanitized correctly even if math and svg are not in the allowlist.
You are likely to be vulnerable to this issue if you use Sanitize's relaxed config or a custom config that allows one or more of the following HTML elements:
iframemathnoembednoframesnoscriptplaintextscriptstylesvgxmp
Impact
Using carefully crafted input, an attacker may be able to sneak arbitrary HTML through Sanitize, potentially resulting in XSS (cross-site scripting) or other undesired behavior when that HTML is rendered in a browser.
Releases
This problem has been fixed in Sanitize 5.2.1.
Workarounds
If upgrading is not possible, a workaround is to override the default value of Sanitize's :remove_contents config option with the following value, which ensures that the contents of math and svg elements (among others) are removed entirely when those elements are not in the allowlist:
For example, if you currently use Sanitize's relaxed config, you can create a custom config object that overrides the default value of :remove_contents like this:
You would then pass this custom config to Sanitize when sanitizing HTML.
For more information
If you have any questions or comments about this advisory:
- Open an issue in the Sanitize repo.
- See Sanitize's security policy.
Credits
Many thanks to Michal Bentkowski of Securitum for reporting this bug and helping to verify the fix.
References
Ссылки
- https://github.com/rgrove/sanitize/security/advisories/GHSA-p4x4-rw2p-8j8m
- https://nvd.nist.gov/vuln/detail/CVE-2020-4054
- https://github.com/rgrove/sanitize/commit/a11498de9e283cd457b35ee252983662f7452aa9
- https://github.com/rgrove/sanitize/releases/tag/v5.2.1
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sanitize/CVE-2020-4054.yml
- https://usn.ubuntu.com/4543-1
- https://www.debian.org/security/2020/dsa-4730
Пакеты
sanitize
>= 3.0.0, < 5.2.1
5.2.1
Связанные уязвимости
In Sanitize (RubyGem sanitize) greater than or equal to 3.0.0 and less than 5.2.1, there is a cross-site scripting vulnerability. When HTML is sanitized using Sanitize's "relaxed" config, or a custom config that allows certain elements, some content in a math or svg element may not be sanitized correctly even if math and svg are not in the allowlist. You are likely to be vulnerable to this issue if you use Sanitize's relaxed config or a custom config that allows one or more of the following HTML elements: iframe, math, noembed, noframes, noscript, plaintext, script, style, svg, xmp. Using carefully crafted input, an attacker may be able to sneak arbitrary HTML through Sanitize, potentially resulting in XSS (cross-site scripting) or other undesired behavior when that HTML is rendered in a browser. This has been fixed in 5.2.1.
In Sanitize (RubyGem sanitize) greater than or equal to 3.0.0 and less than 5.2.1, there is a cross-site scripting vulnerability. When HTML is sanitized using Sanitize's "relaxed" config, or a custom config that allows certain elements, some content in a math or svg element may not be sanitized correctly even if math and svg are not in the allowlist. You are likely to be vulnerable to this issue if you use Sanitize's relaxed config or a custom config that allows one or more of the following HTML elements: iframe, math, noembed, noframes, noscript, plaintext, script, style, svg, xmp. Using carefully crafted input, an attacker may be able to sneak arbitrary HTML through Sanitize, potentially resulting in XSS (cross-site scripting) or other undesired behavior when that HTML is rendered in a browser. This has been fixed in 5.2.1.
In Sanitize (RubyGem sanitize) greater than or equal to 3.0.0 and less ...
Уязвимость библиотеки Sanitize для языка программирования Ruby, связанная с недостатками используемых мер по защите структур веб-страницы, позволяющая нарушителю получить доступ к конфиденциальным данным, нарушить их целостность, а также вызвать отказ в обслуживании