There is an issue with grub2 before version 2.06 while handling symlink on ext filesystems. A filesystem containing a symbolic link with an inode size of UINT32_MAX causes an arithmetic overflow leading to a zero-sized memory allocation with subsequent heap-based buffer overflow.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-14311
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-14311
• https://security.gentoo.org/glsa/202104-05
• https://usn.ubuntu.com/4432-1/
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00016.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00017.html
• http://www.openwall.com/lists/oss-security/2021/09/17/2
• http://www.openwall.com/lists/oss-security/2021/09/17/4
• http://www.openwall.com/lists/oss-security/2021/09/21/1