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An easy safelist-based HTML-sanitizing tool.

Project description

Bleach is an allowed-list-based HTML sanitizing library that escapes or strips markup and attributes.

Bleach can also linkify text safely, applying filters that Django’s urlize filter cannot, and optionally setting rel attributes, even on links already in the text.

Bleach is intended for sanitizing text from untrusted sources. If you find yourself jumping through hoops to allow your site administrators to do lots of things, you’re probably outside the use cases. Either trust those users, or don’t.

Because it relies on html5lib, Bleach is as good as modern browsers at dealing with weird, quirky HTML fragments. And any of Bleach’s methods will fix unbalanced or mis-nested tags.

The version on GitHub is the most up-to-date and contains the latest bug fixes. You can find full documentation on ReadTheDocs.



Issue tracker:


#bleach on


Apache License v2; see LICENSE file

Reporting Bugs

For regular bugs, please report them in our issue tracker.

If you believe that you’ve found a security vulnerability, please file a secure bug report in our bug tracker or send an email to security AT mozilla DOT org.

For more information on security-related bug disclosure and the PGP key to use for sending encrypted mail or to verify responses received from that address, please read our wiki page at

Installing Bleach

Bleach is available on PyPI, so you can install it with pip:

$ pip install bleach

Or with easy_install:

$ easy_install bleach

Upgrading Bleach

Basic use

The simplest way to use Bleach is:

>>> import bleach

>>> bleach.clean('an <script>evil()</script> example')
u'an &lt;script&gt;evil()&lt;/script&gt; example'

>>> bleach.linkify('an url')
u'an <a href="" rel="nofollow"></a> url


Bleach is a security-related library.

We have a responsible security vulnerability reporting process. Please use that if you’re reporting a security issue.

Security issues are fixed in private. After we land such a fix, we’ll do a release.

For every release, we mark security issues we’ve fixed in the CHANGES in the Security issues section. We include relevant CVE links.

Code of conduct

This project and repository is governed by Mozilla’s code of conduct and etiquette guidelines. For more details please see the Mozilla Community Participation Guidelines and Developer Etiquette Guidelines.

Bleach changes

Version 2.1.4 (August 16th, 2018)

Security fixes


Backwards incompatible changes

  • Dropped support for Python 3.3. (#328)



Bug fixes

  • Handle ambiguous ampersands in correctly. (#359)

Version 2.1.3 (March 5th, 2018)

Security fixes

  • Attributes that have URI values weren’t properly sanitized if the values contained character entities. Using character entities, it was possible to construct a URI value with a scheme that was not allowed that would slide through unsanitized.

    This security issue was introduced in Bleach 2.1. Anyone using Bleach 2.1 is highly encouraged to upgrade.

Backwards incompatible changes




Bug fixes

  • Fixed some other edge cases for attribute URI value sanitizing and improved testing of this code.

Version 2.1.2 (December 7th, 2017)

Security fixes


Backwards incompatible changes




Bug fixes

  • Support html5lib-python 1.0.1. (#337)

  • Add deprecation warning for supporting html5lib-python < 1.0.

  • Switch to semver.

Version 2.1.1 (October 2nd, 2017)

Security fixes


Backwards incompatible changes




Bug fixes

  • Fix opening files when LANG=. (#324)

Version 2.1 (September 28th, 2017)

Security fixes

  • Convert control characters (backspace particularly) to “?” preventing malicious copy-and-paste situations. (#298)

    See for more details.

    This affects all previous versions of Bleach. Check the comments on that issue for ways to alleviate the issue if you can’t upgrade to Bleach 2.1.

Backwards incompatible changes

  • Redid versioning. bleach.VERSION is no longer available. Use the string version at bleach.__version__ and parse it with pkg_resources.parse_version. (#307)

  • clean, linkify: linkify and clean should only accept text types; thank you, Janusz! (#292)

  • clean, linkify: accept only unicode or utf-8-encoded str (#176)


Bug fixes

  • bleach.clean() no longer unescapes entities including ones that are missing a ; at the end which can happen in urls and other places. (#143)

  • linkify: fix http links inside of mailto links; thank you, sedrubal! (#300)

  • clarify security policy in docs (#303)

  • fix dependency specification for html5lib 1.0b8, 1.0b9, and 1.0b10; thank you, Zoltán! (#268)

  • add Bleach vs. html5lib comparison to README; thank you, Stu Cox! (#278)

  • fix KeyError exceptions on tags without href attr; thank you, Alex Defsen! (#273)

  • add test website and scripts to test bleach.clean() output in browser; thank you, Greg Guthe!

Version 2.0 (March 8th, 2017)

Security fixes

  • None

Backwards incompatible changes

  • Removed support for Python 2.6. #206

  • Removed support for Python 3.2. #224

  • Bleach no longer supports html5lib < 0.99999999 (8 9s).

    This version is a rewrite to use the new sanitizing API since the old one was dropped in html5lib 0.99999999 (8 9s).

    If you’re using 0.9999999 (7 9s) upgrade to 0.99999999 (8 9s) or higher.

    If you’re using 1.0b8 (equivalent to 0.9999999 (7 9s)), upgrade to 1.0b9 (equivalent to 0.99999999 (8 9s)) or higher.

  • bleach.clean and friends were rewritten

    clean was reimplemented as an html5lib filter and happens at a different step in the HTML parsing -> traversing -> serializing process. Because of that, there are some differences in clean’s output as compared with previous versions.

    Amongst other things, this version will add end tags even if the tag in question is to be escaped.

  • bleach.clean and friends attribute callables now take three arguments: tag, attribute name and attribute value. Previously they only took attribute name and attribute value.

    All attribute callables will need to be updated.

  • bleach.linkify was rewritten

    linkify was reimplemented as an html5lib Filter. As such, it no longer accepts a tokenizer argument.

    The callback functions for adjusting link attributes now takes a namespaced attribute.

    Previously you’d do something like this:

    def check_protocol(attrs, is_new):
        if not attrs.get('href', '').startswith('http:', 'https:')):
            return None
        return attrs

    Now it’s more like this:

    def check_protocol(attrs, is_new):
        if not attrs.get((None, u'href'), u'').startswith(('http:', 'https:')):
            #            ^^^^^^^^^^^^^^^
            return None
        return attrs

    Further, you need to make sure you’re always using unicode values. If you don’t then html5lib will raise an assertion error that the value is not unicode.

    All linkify filters will need to be updated.

  • bleach.linkify and friends had a skip_pre argument–that’s been replaced with a more general skip_tags argument.

    Before, you might do:

    bleach.linkify(some_text, skip_pre=True)

    The equivalent with Bleach 2.0 is:

    bleach.linkify(some_text, skip_tags=['pre'])

    You can skip other tags, too, like style or script or other places where you don’t want linkification happening.

    All uses of linkify that use skip_pre will need to be updated.


  • Supports Python 3.6.

  • Supports html5lib >= 0.99999999 (8 9s).

  • There’s a bleach.sanitizer.Cleaner class that you can instantiate with your favorite clean settings for easy reuse.

  • There’s a bleach.linkifier.Linker class that you can instantiate with your favorite linkify settings for easy reuse.

  • There’s a bleach.linkifier.LinkifyFilter which is an htm5lib filter that you can pass as a filter to bleach.sanitizer.Cleaner allowing you to clean and linkify in one pass.

  • bleach.clean and friends can now take a callable as an attributes arg value.

  • Tons of bug fixes.

  • Cleaned up tests.

  • Documentation fixes.

Version 1.5 (November 4th, 2016)

Security fixes

  • None

Backwards incompatible changes

  • clean: The list of ALLOWED_PROTOCOLS now defaults to http, https and mailto.

    Previously it was a long list of protocols something like ed2k, ftp, http, https, irc, mailto, news, gopher, nntp, telnet, webcal, xmpp, callto, feed, urn, aim, rsync, tag, ssh, sftp, rtsp, afs, data. #149


  • clean: Added protocols to arguments list to let you override the list of allowed protocols. Thank you, Andreas Malecki! #149

  • linkify: Fix a bug involving periods at the end of an email address. Thank you, Lorenz Schori! #219

  • linkify: Fix linkification of non-ascii ports. Thank you Alexandre, Macabies! #207

  • linkify: Fix linkify inappropriately removing node tails when dropping nodes. #132

  • Fixed a test that failed periodically. #161

  • Switched from nose to py.test. #204

  • Add test matrix for all supported Python and html5lib versions. #230

  • Limit to html5lib >=0.999,!=0.9999,!=0.99999,<0.99999999 because 0.9999 and 0.99999 are busted.

  • Add support for python test. #97

Version 1.4.3 (May 23rd, 2016)

Security fixes

  • None


  • Limit to html5lib >=0.999,<0.99999999 because of impending change to sanitizer api. #195

Version 1.4.2 (September 11, 2015)


  • linkify: Fix hang in linkify with parse_email=True. #124

  • linkify: Fix crash in linkify when removing a link that is a first-child. #136

  • Updated TLDs.

  • linkify: Don’t remove exterior brackets when linkifying. #146

Version 1.4.1 (December 15, 2014)


  • Consistent order of attributes in output.

  • Python 3.4 support.

Version 1.4 (January 12, 2014)


  • linkify: Update linkify to use etree type Treewalker instead of simpletree.

  • Updated html5lib to version >=0.999.

  • Update all code to be compatible with Python 3 and 2 using six.

  • Switch to Apache License.

Version 1.3

  • Used by Python 3-only fork.

Version 1.2.2 (May 18, 2013)

  • Pin html5lib to version 0.95 for now due to major API break.

Version 1.2.1 (February 19, 2013)

  • clean() no longer considers feed: an acceptable protocol due to inconsistencies in browser behavior.

Version 1.2 (January 28, 2013)

  • linkify() has changed considerably. Many keyword arguments have been replaced with a single callbacks list. Please see the documentation for more information.

  • Bleach will no longer consider unacceptable protocols when linkifying.

  • linkify() now takes a tokenizer argument that allows it to skip sanitization.

  • delinkify() is gone.

  • Removed exception handling from _render. clean() and linkify() may now throw.

  • linkify() correctly ignores case for protocols and domain names.

  • linkify() correctly handles markup within an <a> tag.

Version 1.1.5

Version 1.1.4

Version 1.1.3 (July 10, 2012)

  • Fix parsing bare URLs when parse_email=True.

Version 1.1.2 (June 1, 2012)

  • Fix hang in style attribute sanitizer. (#61)

  • Allow / in style attribute values.

Version 1.1.1 (February 17, 2012)

  • Fix tokenizer for html5lib 0.9.5.

Version 1.1.0 (October 24, 2011)

  • linkify() now understands port numbers. (#38)

  • Documented character encoding behavior. (#41)

  • Add an optional target argument to linkify().

  • Add delinkify() method. (#45)

  • Support subdomain whitelist for delinkify(). (#47, #48)

Version 1.0.4 (September 2, 2011)

  • Switch to SemVer git tags.

  • Make linkify() smarter about trailing punctuation. (#30)

  • Pass exc_info to logger during rendering issues.

  • Add wildcard key for attributes. (#19)

  • Make linkify() use the HTMLSanitizer tokenizer. (#36)

  • Fix URLs wrapped in parentheses. (#23)

  • Make linkify() UTF-8 safe. (#33)

Version 1.0.3 (June 14, 2011)

  • linkify() works with 3rd level domains. (#24)

  • clean() supports vendor prefixes in style values. (#31, #32)

  • Fix linkify() email escaping.

Version 1.0.2 (June 6, 2011)

  • linkify() supports email addresses.

  • clean() supports callables in attributes filter.

Version 1.0.1 (April 12, 2011)

  • linkify() doesn’t drop trailing slashes. (#21)

  • linkify() won’t linkify ‘’. (#22)

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