Buffer Overflow Vulnerability in Matrix libolm Affects Element Web and SchildiChat Web

CVE-2021-44538

What is CVE-2021-44538?

Matrix libolm, prior to version 3.2.7, contains a buffer overflow vulnerability in the olm_session_describe function. This function is responsible for managing the state of a cryptographic channel between two parties, allowing an attacker to manipulate the session state. By crafting a specific sequence of messages, an attacker could trigger a buffer overflow during the call to olm_session_describe, particularly when using certain buffer sizes. The vulnerable state is partially controllable by the attacker, limited to ASCII characters such as spaces and digits, thus posing a serious risk to the integrity of the session.

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