Acrobat Reader versions 20.005.30636, 24.002.21005, 24.001.30159, 20.005.30655, 24.002.20965, 24.002.20964, 24.001.30123, 24.003.20054 and earlier are affected by a Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability that could lead to arbitrary code execution. This vulnerability arises when the timing of actions changes the state of a resource between the checking of a condition and the use of the resource, allowing an attacker to manipulate the resource in a harmful way. Exploitation of this issue requires user interaction in that a victim must open a malicious file.
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.