CVE-2022-21688: 
Python vulnerability analysis and mitigation

OnionShare, an open-source tool for securely sharing files and hosting websites using the Tor network, was found to be vulnerable to a denial of service attack (CVE-2022-21688). The vulnerability was discovered during a penetration test conducted by Radically Open Security between September 26 and October 8, 2021. The issue affects versions prior to 2.5 and involves an undisclosed vulnerability in the QT image parsing component (GitHub Advisory).

The vulnerability is classified as an Out-of-bounds Read (CWE-125) with a CVSS 3.1 base score of 7.5 (HIGH). The issue involves image parsing in the QT component where approximately 20 bytes of data can trigger 2GB of memory consumption, and this can be executed multiple times. The vulnerability specifically requires rendering in the history tab, indicating that some user interaction is necessary for exploitation (NVD, GitHub Advisory).

When exploited, an attacker with knowledge of the Onion service address in public mode or with authentication in private mode can perform a Denial of Service attack. The attack quickly results in out-of-memory conditions for the server, though the impact is considered elevated rather than critical due to the requirement of desktop application usage with rendered history (GitHub Advisory).

The vulnerability has been patched in OnionShare version 2.5. The fix includes sanitizing the path parameter in the History item widget to be plain text and various other security improvements (GitHub Release).