python-markdown2 through 2.3.8 allows XSS because element names are mishandled unless a \w+ match succeeds. For example, an attack might use elementname@ or elementname- with an onclick attribute.
References
- https://nvd.nist.gov/vuln/detail/CVE-2020-11888
- https://github.com/trentm/python-markdown2/issues/348
- http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00031.html
- http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00035.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6XOAIRJJCZNJUALXDHSIGH5PS2H63A3J/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/AQLRBGRVRRZK7P5SFL2MNGXFX37YHJAV/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PN6QSHRFZXRQAYZJQ4MOW5MKIXBYOMED/
- https://github.com/advisories/GHSA-fv3h-8x5j-pvgq