In the Linux kernel before 5.7.8, fs/nfsd/vfs.c (in the NFS server) can set incorrect permissions on new filesystem objects when the filesystem lacks ACL support, aka CID-22cf8419f131. This occurs because the current umask is not considered.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-24394
• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=962254
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.7.8
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=22cf8419f1319ff87ec759d0ebdff4cbafaee832
• https://security.netapp.com/advisory/ntap-20200904-0003/
• https://usn.ubuntu.com/4465-1/
• https://usn.ubuntu.com/4483-1/
• https://usn.ubuntu.com/4485-1/
• https://www.oracle.com/security-alerts/cpuApr2021.html
• http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00007.html
• https://www.starwindsoftware.com/security/sw-20210325-0004/