It was reported that python-bleach, a whitelist-based HTML-sanitizing library, is prone to a mutation XSS vulnerability in bleach.clean when'svg' or 'math' are in the allowed tags, 'p' or 'br' are in allowed tags, 'style', 'title', 'noscript', 'script', 'textarea', 'noframes','iframe', or 'xmp' are in allowed tags and 'strip_comments=False' is set.

The remote Redhat Enterprise Linux 7 / 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:0781 advisory.

    Red Hat Ansible Automation Platform integrates Red Hat's automation suite consisting of Red Hat Ansible     Tower, Red Hat Ansible Engine, Automation Hub and use-case specific capabilities for Microsoft Windows,     network, security, and more, along with Software-as-a-Service (SaaS)-based capabilities and features for     organization-wide effectiveness.

    This update fixes various bugs and adds enhancements. Documentation for     these changes is available from the Release Notes document linked to in the     References section.

    Security Fix(es):

    * node-notifier: nodejs-node-notifier: command injection due to the options params not being sanitised     when being passed an array (CVE-2020-7789)
    * nodejs-ajv: prototype pollution via crafted JSON schema in ajv.validate function (CVE-2020-15366)
    * django: Potential directory-traversal via archive.extract() (CVE-2021-3281)
    * python-pygments: infinite loop in SML lexer may lead to DoS (CVE-2021-20270)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

This update for python-bleach fixes the following issues :

  - CVE-2021-23980: Fixed mutation XSS on bleach.clean with     specific combinations of allowed tags (boo#1184547)

Update to 3.1.5 :

  - replace missing ``setuptools`` dependency with     ``packaging``. Thank you Benjamin Peterson.

Update to 3.1.4 (boo#1168280, CVE-2020-6817) :

  - ``bleach.clean`` behavior parsing style attributes could     result in a regular expression denial of service     (ReDoS). Calls to ``bleach.clean`` with an allowed tag     with an allowed ``style`` attribute were vulnerable to     ReDoS. For example, ``bleach.clean(..., attributes=('a':
    ['style']))``.

  - Style attributes with dashes, or single or double quoted     values are cleaned instead of passed through.

update to 3.1.3 (boo#1167379, CVE-2020-6816) :

  - Add relative link to code of conduct. (#442)

  - Drop deprecated 'setup.py test' support. (#507)

  - Fix typo: curren -> current in tests/test_clean.py     (#504)

  - Test on PyPy 7

  - Drop test support for end of life Python 3.4

  - ``bleach.clean`` behavior parsing embedded MathML and     SVG content with RCDATA tags did not match browser     behavior and could result in a mutation XSS. Calls to     ``bleach.clean`` with ``strip=False`` and ``math`` or     ``svg`` tags and one or more of the RCDATA tags     ``script``, ``noscript``, ``style``, ``noframes``,     ``iframe``, ``noembed``, or ``xmp`` in the allowed tags     whitelist were vulnerable to a mutation XSS.

The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8077-1 advisory.

    It was discovered that Bleach did not properly sanitize URI attributes containing character entities. An     attacker could possibly use this issue to construct a URI with a disallowed scheme that would bypass     sanitization, leading to cross-site scripting. This issue only affected Ubuntu 18.04 LTS. (CVE-2018-7753)

    Yaniv Nizry discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing     HTML with the noscript tag and a raw tag in the allowed tags list. An attacker could possibly use this     issue to inject malicious content, leading to cross-site scripting. This issue only affected Ubuntu 18.04     LTS. (CVE-2020-6802)

    Yaniv Nizry discovered that Bleach was vulnerable to a mutation cross-site scripting issue when sanitizing     HTML with RCDATA together with svg or math tags in the allowed tags list. An attacker could possibly use     this issue to inject malicious content, leading to cross-site scripting. (CVE-2020-6816)

    It was discovered that Bleach incorrectly handled parsing of style attributes when sanitizing HTML. An     attacker could possibly use this issue to perform a regular expression denial of service, leading to     excessive resource consumption. (CVE-2020-6817)

    Yaniv Nizry and Micha Bentkowski discovered that Bleach was vulnerable to a mutation cross-site     scripting issue when sanitizing HTML with certain combinations of allowed tags. An attacker could possibly     use this issue to inject malicious content, leading to cross-site scripting. (CVE-2021-23980)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It was discovered that there was a cross-site scripting (XSS) vulnerability in python-bleach, a whitelist-based HTML sanitisation library.

For Debian 9 'Stretch', this problem has been fixed in version 2.0-1+deb9u1.

We recommend that you upgrade your python-bleach packages.

For the detailed security status of python-bleach please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/python-bleach

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - A mutation XSS affects users calling bleach.clean with all of: svg or math in the allowed tags p or br in     allowed tags style, title, noscript, script, textarea, noframes, iframe, or xmp in allowed tags the     keyword argument strip_comments=False Note: none of the above tags are in the default allowed tags and     strip_comments defaults to True. (CVE-2021-23980)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Published	Updated	Severity
148756	Debian DSA-4892-1 : python-bleach - security update	Nessus	Debian Local Security Checks	4/19/2021	1/12/2024	medium
194285	RHEL 7 / 8 : Red Hat Ansible Automation Platform 1.2.2 (RHSA-2021:0781)	Nessus	Red Hat Local Security Checks	4/28/2024	11/7/2024	medium
148606	openSUSE Security Update : python-bleach (openSUSE-2021-552)	Nessus	SuSE Local Security Checks	4/15/2021	1/4/2024	medium
301534	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Bleach vulnerabilities (USN-8077-1)	Nessus	Ubuntu Local Security Checks	3/9/2026	3/9/2026	critical
148363	Debian DLA-2620-1 : python-bleach security update	Nessus	Debian Local Security Checks	4/7/2021	1/12/2024	medium
251172	Linux Distros Unpatched Vulnerability : CVE-2021-23980	Nessus	Misc.	8/18/2025	3/10/2026	medium

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