A bug in the handling of the pipelined requests in Apache Tomcat 9.0.0.M1 to 9.0.0.M18, 8.5.0 to 8.5.12, 8.0.0.RC1 to 8.0.42, 7.0.0 to 7.0.76, and 6.0.0 to 6.0.52, when send file was used, results in the pipelined request being lost when send file processing of the previous request completed. This could result in responses appearing to be sent for the wrong request. For example, a user agent that sent requests A, B and C could see the correct response for request A, the response for request C for request B and no response for request C.
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html
https://security.netapp.com/advisory/ntap-20180614-0001/
https://security.gentoo.org/glsa/201705-09
https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03730en_us
https://access.redhat.com/errata/RHSA-2017:3081
https://access.redhat.com/errata/RHSA-2017:3080
https://access.redhat.com/errata/RHSA-2017:2494
https://access.redhat.com/errata/RHSA-2017:2493
https://access.redhat.com/errata/RHSA-2017:1802
https://access.redhat.com/errata/RHSA-2017:1801
http://www.securitytracker.com/id/1038218
http://www.oracle.com/technetwork/security-advisory/cpujul2017-3236622.html
http://www.debian.org/security/2017/dsa-3843