Bump github.com/microcosm-cc/bluemonday from 1.0.4 to 1.0.20

[dependabot]

Bumps github.com/microcosm-cc/bluemonday from 1.0.4 to 1.0.20.

Release notes

Sourced from github.com/microcosm-cc/bluemonday's releases.

Updated x/net/html

This is an update of dependencies, specifically it updates the HTML parser within go/net/html.

The update removes a capability, Microsoft style comments that allow browser conditionals no longer works. This is due to a fix on the part of the Go team to prevent XSS within HTML comments, and the commit in question is here golang/net@06994584 . There is no easy to see safe way to restore that functionality without adding more risk to those who .AllowComments() and so I am accepting that this non-standard use of HTML comments is no longer supported.

As part of this version, the older release of v1.0.19 is retracted.

Add SVG inline images, improve RGB color and length matching, fix bug

What's Changed

• css: improve RGB hex color and length matching by @​hochhaus in microcosm-cc/bluemonday#142
• css: add support for image/svg+xml for data-uri inline images
• html: fix double-escaping of content within HTML attributes
• tests: added more tests to provide examples of proofs of some open issues

New Contributors

• @​hochhaus made their first contribution in microcosm-cc/bluemonday#142

Full Changelog: microcosm-cc/bluemonday@v1.0.18...v1.0.19

Fix bug in iframe sandboxvalues

What's Changed

• Fix incorrect handling of iframe SandboxValues by @​kiwiz in microcosm-cc/bluemonday#138

Full Changelog: microcosm-cc/bluemonday@v1.0.17...v1.0.18

Add support for the "sandbox" attribute on the "iframe" element

As per microcosm-cc/bluemonday#135 @​kiwiz has added support to bluemonday that allows the iframe element to correctly declare the security attribute sandbox.

You can read about that attribute here: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-sandbox

No other change is in this release.

Prevent a HTML sanitization vulnerability

CVE-2021-42576

A vulnerability was discovered by https://github.com/TomAnthony https://www.tomanthony.co.uk/ which allowed the contents of a style tag to be leaked unsanitized by bluemonday into the HTML output. Further it was demonstrated that if the form elements select and option were allowed by the policy that this could result in a successful XSS.

You would only be vulnerable to if if you allowed style, select and option in your HTML sanitization policy:

p := bluemonday.NewPolicy()
p.AllowElements("style","select")
html := p.Sanitize(`<select><option><style><script>alert(1)</script>`)
fmt.Println(html)

bluemonday very strongly recommends not allowing the style element in a policy. It is fundamentally unsafe as we do not have a CSS sanitizer and the content is passed through unmodified.

bluemonday has been updated to explicitly suppress style and script elements by default even if you do allow them by policy as these are considered unsafe. If you have a use-case for using bluemonday whilst trusting the input then you can assert this via p.AllowUnsafe(true) which will let style and script through if the policy also allows them.

... (truncated)

Commits

• 705c34a Updated x/net/html to ensure latest version from the Go team, retracted v1.0....
• 84409dd Only test n-1 Go versions
• 8fc9802 Merge branch 'main' of github.com:microcosm-cc/bluemonday into main
• c66f9ff Updated Go version, retract old versions of this package which are always con...
• a232bac Removed outdated build badge
• 97a5b1f Test recent Go versions
• 9ec48cf Test recent Go versions
• d4b11cb Added funding file
• 9ef01f7 Closes #134 add tests to show all sanitize methods are roughly equal in time
• ed50dcc Closes #139 by demonstrating in a test that it still works
• Additional commits viewable in compare view

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