As described by [Red Hat](https://access.redhat.com/security/cve/CVE-2023-4911) and in [CVE-2023-4911](https://www.cve.org/CVERecord?id=CVE-2023-4911):
A buffer overflow was discovered in the GNU C Library's dynamic loader ld.so while processing the `GLIBC_TUNABLES` environment variable. This issue could allow a local attacker to use maliciously crafted `GLIBC_TUNABLES` environment variables when launching binaries with SUID permission to execute code with elevated privileges.
More detail is available in the [public disclosure](https://www.openwall.com/lists/oss-security/2023/10/03/2) by [Qualys](https://blog.qualys.com/vulnerabilities-threat-research/2023/10/03/cve-2023-4911-looney-tunables-local-privilege-escalation-in-the-glibcs-ld-so), the team who discovered the issue.