CVE-2020-11098: 
NixOS vulnerability analysis and mitigation

In FreeRDP before version 2.1.2, there is an out-of-bound read vulnerability in glyph_cache_put function. This vulnerability affects all FreeRDP clients that have the +glyph-cache option enabled. The issue was discovered in early 2020 and was fixed with the release of FreeRDP version 2.1.2 on June 22, 2020 (GitHub Advisory, FreeRDP Release).

The vulnerability (CVE-2020-11098) is characterized by an out-of-bounds read condition in the glyph_cache_put function. The issue occurs due to improper validation of the index parameter against the glyph cache size. The vulnerability has been assigned a CVSS v3.1 base score of 6.5 (Medium), with attack vector being Network, attack complexity Low, and requiring no privileges or user interaction (Ubuntu CVE).

When exploited, this vulnerability could lead to unauthorized access to memory locations outside the intended boundaries. The primary impact includes potential information disclosure through memory reads and possible denial of service conditions. The vulnerability affects the confidentiality (Low) and availability (Low) of the system, while having no impact on integrity (Ubuntu CVE).

The vulnerability can be exploited remotely through the network with low attack complexity. No special privileges or user interaction is required for exploitation. The vulnerability specifically affects FreeRDP clients with the +glyph-cache option enabled (GitHub Advisory).

The primary mitigation is to upgrade to FreeRDP version 2.1.2 or later, which contains the fix for this vulnerability. For users unable to upgrade immediately, a workaround is available by disabling the glyph-cache feature. The fix was implemented through a patch that corrected the index validation in the glyph_cache_put function (FreeRDP Commit).