The uncompress_buffer function in src/server/simple_wml.cpp in Wesnoth before r33069 allows remote attackers to cause a denial of service via a large compressed WML document.
The Python AI module in Wesnoth 1.4.x and 1.5 before 1.5.11 allows remote attackers to escape the sandbox and execute arbitrary code by using a whitelisted module that imports an unsafe module, then using a hierarchical module name to access the unsafe module through the whitelisted module.