* Allow simple alphanumeric style attribute values in the htmlscrubber. This

  should be safe from javascript attacks.

1 files changed, 7 insertions, 1 deletions

diff --git a/doc/plugins/htmlscrubber.mdwn b/doc/plugins/htmlscrubber.mdwn
index 7962b3b52..cc749e2dc 100644
--- a/doc/plugins/htmlscrubber.mdwn
+++ b/doc/plugins/htmlscrubber.mdwn
@@ -7,7 +7,12 @@ to avoid XSS attacks and the like.
 It excludes all html tags and attributes except for those that are
 whitelisted using the same lists as used by Mark Pilgrim's Universal Feed
 Parser, documented at <http://feedparser.org/docs/html-sanitization.html>.
-Notably it strips `style`, `link`, and the `style` attribute.
+Notably it strips `style` and `link`.
+
+For the `style` attribute, it varys slightly from the Universal Feed
+Parser, accepting simple alphanumeric style attributes (style="foo"), but
+stripping anything more complex to avoid any of the ways to insert
+JavaScript via style attributes.
 
 It uses the [[cpan HTML::Scrubber]] perl module to perform its html
 sanitisation, and this perl module also deals with various entity encoding
@@ -36,3 +41,4 @@ plugin is active:
 * <span style="background: url(javascript:window.location='http://example.org/')">CSS script test</span>
 * <span style="&#x61;&#x6e;&#x79;&#x3a;&#x20;&#x65;&#x78;&#x70;&#x72;&#x65;&#x73;&#x73;&#x69;&#x6f;&#x6e;&#x28;&#x77;&#x69;&#x6e;&#x64;&#x6f;&#x77;&#x2e;&#x6c;&#x6f;&#x63;&#x61;&#x74;&#x69;&#x6f;&#x6e;&#x3d;&#x27;&#x68;&#x74;&#x74;&#x70;&#x3a;&#x2f;&#x2f;&#x65;&#x78;&#x61;&#x6d;&#x70;&#x6c;&#x65;&#x2e;&#x6f;&#x72;&#x67;&#x2f;&#x27;&#x29;">entity-encoded CSS script test</span>
 * <span style="&#97;&#110;&#121;&#58;&#32;&#101;&#120;&#112;&#114;&#101;&#115;&#115;&#105;&#111;&#110;&#40;&#119;&#105;&#110;&#100;&#111;&#119;&#46;&#108;&#111;&#99;&#97;&#116;&#105;&#111;&#110;&#61;&#39;&#104;&#116;&#116;&#112;&#58;&#47;&#47;&#101;&#120;&#97;&#109;&#112;&#108;&#101;&#46;&#111;&#114;&#103;&#47;&#39;&#41;">entity-encoded CSS script test</span>
+* <span style="pretty">OTOH, this is ok, and will be accepted</a>