CVE-2020-11888: 
Python vulnerability analysis and mitigation

CVE-2020-11888 is a cross-site scripting (XSS) vulnerability affecting python-markdown2 through version 2.3.8. The vulnerability exists because element names are mishandled unless a \w+ match succeeds. For example, an attacker could exploit this by using elementname@ or elementname- with an onclick attribute (CVE Mitre, NVD).

The vulnerability stems from improper validation of element names in the markdown parsing process. The issue specifically occurs when the parser fails to properly sanitize input that doesn't match the \w+ pattern, allowing attackers to bypass the safe_mode protection even when it's set to true (Github Issue).

When exploited, this vulnerability allows attackers to execute cross-site scripting (XSS) attacks through unsanitized input, potentially leading to the execution of malicious scripts in the context of the user's browser (OpenSUSE Security).

The vulnerability can be exploited by crafting specific markdown content that bypasses the element name validation. This requires the attacker to submit malicious content to a system that uses python-markdown2 for processing markdown to HTML conversion (Github Issue).

The vulnerability was fixed in python-markdown2 version 2.3.9, which includes XSS fixes from pull requests #350 and #353. Users are advised to upgrade to this version or later (Fedora Update).