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Sanitization rules
This page was initially seeded with the sanitization lists and rules implemented by the html5lib sanitizer, which in turn was based on Jacques Distler's branch of Instiki, which in turn was based on the sanitization logic in the Universal Feed Parser.
It is hoped that others will add, update, and extend this list based on their experiences in their own products, and furthermore that some will update their products based on these lists. One such product isweight gain(diffs). Another product is bloglines.
As a suggestion but not as a requirement: people who do update their products to reflect information from this list are encouraged to add a link to this page as a comment in the hopes that it will encourage subsequent maintainers to keep this page up to date.
As a convenience, this script (source) converts these lists into a syntax shared by a number of common programming languages.
Acceptable Elements
- a
- abbr
- acronym
- address
- area
- b
- bdo
- big
- blockquote
- br
- button
- caption
- center
- cite
- code
- col
- colgroup
- dd
- del
- dfn
- dir
- div
- dl
- dt
- em
- fieldset
- font
- form
- h1
- h2
- h3
- h4
- h5
- h6
- hr
- i
- img
- input
- ins
- kbd
- label
- legend
- li
- map
- menu
- ol
- optgroup
- option
- p
- pre
- q
- s
- samp
- select
- small
- span
- strike
- strong
- sub
- sup
- table
- tbody
- td
- textarea
- tfoot
- th
- thead
- tr
- tt
- u
- ul
- var
- wbr
mathml Elements
- maction
- math
- merror
- mfrac
- mi
- mmultiscripts
- mn
- mo
- mover
- mpadded
- mphantom
- mprescripts
- mroot
- mrow
- mspace
- msqrt
- mstyle
- msub
- msubsup
- msup
- mtable
- mtd
- mtext
- mtr
- munder
- munderover
- none
svg Elements
- a
- animate
- animateColor
- animateMotion
- animateTransform
- circle
- defs
- desc
- ellipse
- font-face
- font-face-name
- font-face-src
- g
- glyph
- hkern
- image
- linearGradient
- line
- marker
- metadata
- missing-glyph
- mpath
- path
- polygon
- polyline
- radialGradient
- rect
- set
- stop
- svg
- switch
- text
- title
- tspan
- use
Acceptable Attributes
- abbr
- accept
- accept-charset
- accesskey
- action
- align
- alt
- axis
- border
- cellpadding
- cellspacing
- char
- charoff
- charset
- checked
- cite
- class
- clear
- cols
- colspan
- color
- compact
- coords
- datetime
- dir
- disabled
- enctype
- for
- frame
- headers
- height
- href
- hreflang
- hspace
- id
- ismap
- label
- lang
- longdesc
- maxlength
- media
- method
- multiple
- name
- nohref
- noshade
- nowrap
- prompt
- readonly
- rel
- rev
- rows
- rowspan
- rules
- scope
- selected
- shape
- size
- span
- src
- start
- style
- summary
- tabindex
- target
- title
- type
- usemap
- valign
- value
- vspace
- width
- xml:lang
mathml Attributes
- actiontype
- align
- columnalign
- columnalign
- columnalign
- columnlines
- columnspacing
- columnspan
- depth
- display
- displaystyle
- equalcolumns
- equalrows
- fence
- fontstyle
- fontweight
- frame
- height
- linethickness
- lspace
- mathbackground
- mathcolor
- mathvariant
- mathvariant
- maxsize
- minsize
- other
- rowalign
- rowalign
- rowalign
- rowlines
- rowspacing
- rowspan
- rspace
- scriptlevel
- selection
- separator
- stretchy
- width
- width
- xlink:href
- xlink:show
- xlink:type
- xmlns
- xmlns:xlink
svg Attributes
- accent-height
- accumulate
- additive
- alphabetic
- arabic-form
- ascent
- attributeName
- attributeType
- baseProfile
- bbox
- begin
- by
- calcMode
- cap-height
- class
- color
- color-rendering
- content
- cx
- cy
- d
- dx
- dy
- descent
- display
- dur
- end
- fill
- fill-rule
- font-family
- font-size
- font-stretch
- font-style
- font-variant
- font-weight
- from
- fx
- fy
- g1
- g2
- glyph-name
- gradientUnits
- hanging
- height
- horiz-adv-x
- horiz-origin-x
- id
- ideographic
- k
- keyPoints
- keySplines
- keyTimes
- lang
- marker-end
- marker-mid
- marker-start
- markerHeight
- markerUnits
- markerWidth
- mathematical
- max
- min
- name
- offset
- opacity
- orient
- origin
- overline-position
- overline-thickness
- panose-1
- path
- pathLength
- points
- preserveAspectRatio
- r
- refX
- refY
- repeatCount
- repeatDur
- requiredExtensions
- requiredFeatures
- restart
- rotate
- rx
- ry
- slope
- stemh
- stemv
- stop-color
- stop-opacity
- strikethrough-position
- strikethrough-thickness
- stroke
- stroke-dasharray
- stroke-dashoffset
- stroke-linecap
- stroke-linejoin
- stroke-miterlimit
- stroke-opacity
- stroke-width
- systemLanguage
- target
- text-anchor
- to
- transform
- type
- u1
- u2
- underline-position
- underline-thickness
- unicode
- unicode-range
- units-per-em
- values
- version
- viewBox
- visibility
- width
- widths
- x
- x-height
- x1
- x2
- xlink:actuate
- xlink:arcrole
- xlink:href
- xlink:role
- xlink:show
- xlink:title
- xlink:type
- xml:base
- xml:lang
- xml:space
- xmlns
- xmlns:xlink
- y
- y1
- y2
- zoomAndPan
CSS Rules
First urls matching the following regular expression are removed:
url\s*\(\s*[^\s)]+?\s*\)\s*
The style strings that don't match the following are deemed obfuscated, and ignored entirely:
^([:,;#%.\sa-zA-Z0-9!]|\w-\w|'[\s\w]+'|"[\s\w]+"|\([\d,\s]+\))*$
^(\s*[-\w]+\s*:\s*[^:;]*(;|$))*$
style Properties
- azimuth
- background, background-*
- border, border-*
- clear
- color
- cursor
- direction
- display
- elevation
- float
- font
- font-family
- font-size
- font-style
- font-variant
- font-weight
- height
- letter-spacing
- line-height
- margin, margin-*
- overflow
- padding, padding-*
- pause
- pause-after
- pause-before
- pitch
- pitch-range
- richness
- speak
- speak-header
- speak-numeral
- speak-punctuation
- speech-rate
- stress
- text-align
- text-decoration
- text-indent
- unicode-bidi
- vertical-align
- voice-family
- volume
- white-space
- width
style Property Values
- auto
- aqua
- black
- block
- blue
- bold
- both
- bottom
- brown
- center
- collapse
- dashed
- dotted
- fuchsia
- gray
- green
- !important
- italic
- left
- lime
- maroon
- medium
- none
- navy
- normal
- nowrap
- olive
- pointer
- purple
- red
- right
- solid
- silver
- teal
- top
- transparent
- underline
- white
- yellow
In addition, values that match the following regular expression are valid:
^(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$
svg style Properties
- fill
- fill-opacity
- fill-rule
- stroke
- stroke-width
- stroke-linecap
- stroke-linejoin
- stroke-opacity
URIs
Attributes whose value is a URI
- href
- src
- cite
- action
- longdesc
- xlink:href
- xml:base
URI schemes
- afs
- aim
- callto
- data (see #Safe data URL content types)
- ed2k
- feed
- ftp
- gopher
- http
- https
- irc
- mailto
- news
- nntp
- rsync
- rtsp
- sftp
- ssh
- tag
- tel
- telnet
- urn
- webcal
- wtai
- xmpp
Safe data URL content types
Note: This section is being discussed.
- text/plain
- image/gif
- image/jpeg
- image/png