[DRE-maint] Bug#963808: ruby-sanitize: CVE-2020-4054: HTML sanitization bypass in Sanitize

[Salvatore Bonaccorso]

Source: ruby-sanitize
Version: 4.6.6-2
Severity: grave
Tags: security upstream
Justification: user security hole

Hi,

The following vulnerability was published for ruby-sanitize.

CVE-2020-4054[0]:
| 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.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2020-4054
    https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-4054
[1] https://github.com/rgrove/sanitize/security/advisories/GHSA-p4x4-rw2p-8j8m
[2] https://github.com/rgrove/sanitize/commit/a11498de9e283cd457b35ee252983662f7452aa9

Regards,
Salvatore