In xsltCopyText in transform.c in libxslt 1.1.33, a pointer variable isn't reset under certain circumstances. If the relevant memory area happened to be freed and reused in a certain way, a bounds check could fail and memory outside a buffer could be written to, or uninitialized data could be disclosed.
http://lists.opensuse.org/opensuse-security-announce/2020-02/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2020-02/msg00015.html
http://lists.opensuse.org/opensuse-security-announce/2020-02/msg00025.html
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00062.html
https://access.redhat.com/errata/RHSA-2020:0514
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15746
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15768
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15914
https://gitlab.gnome.org/GNOME/libxslt/commit/2232473733b7313d67de8836ea3b29eec6e8e285
https://lists.debian.org/debian-lts-announce/2019/10/msg00037.html
https://security.netapp.com/advisory/ntap-20191031-0004/
https://security.netapp.com/advisory/ntap-20200416-0004/
https://usn.ubuntu.com/4164-1/