When responding to new h2c connection requests, Apache Tomcat versions 10.0.0-M1 to 10.0.0, 9.0.0.M1 to 9.0.41 and 8.5.0 to 8.5.61 could duplicate request headers and a limited amount of request body from one request to another meaning user A and user B could both see the results of user A's request.
https://www.oracle.com/security-alerts/cpuoct2021.html
https://www.oracle.com/security-alerts/cpujan2022.html
https://www.oracle.com//security-alerts/cpujul2021.html
https://www.debian.org/security/2021/dsa-4891
https://security.netapp.com/advisory/ntap-20210409-0002/
https://security.gentoo.org/glsa/202208-34
https://lists.debian.org/debian-lts-announce/2021/03/msg00018.html