The software update mechanism as used in Bare Bones Software Yojimbo before 4.0, TextWrangler before 4.5.3, and BBEdit before 10.5.5 does not properly download and verify updates before installation, which allows attackers to perform "tampering or corruption" of the updates.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.