An issue was discovered in Matrix libolm through 3.2.16. Cache-timing attacks can occur due to use of base64 when decoding group session keys. This refers to the libolm implementation of Olm. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
Covert timing channels convey information by modulating some aspect of system behavior over time, so that the program receiving the information can observe system behavior and infer protected information.
In some instances, knowing when data is transmitted between parties can provide a malicious user with privileged information. Also, externally monitoring the timing of operations can potentially reveal sensitive data. For example, a cryptographic operation can expose its internal state if the time it takes to perform the operation varies, based on the state. Covert channels are frequently classified as either storage or timing channels. Some examples of covert timing channels are the system’s paging rate, the time a certain transaction requires to execute, and the time it takes to gain access to a shared bus.