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.
https://soatok.blog/2024/08/14/security-issues-in-matrixs-olm-library/
https://news.ycombinator.com/item?id=41249371
https://gitlab.matrix.org/matrix-org/olm/-/commit/6d4b5b07887821a95b144091c8497d09d377f985