CVE-2023-4911 Looney Tunables: heap overflow in glibc parse_tunables (GLIBC_TUNABLES env var)

CVE-2023-4911 ("Looney Tunables") is a heap buffer overflow in glibc's dynamic loader (ld.so), reachable via the GLIBC_TUNABLES environment variable when processed during program startup of any SUID binary. Call chain: _dl_start -> _dl_main -> __tunables_init -> parse_tunables. Affects glibc 2.34 through 2.37. Local privilege escalation against any SUID-root binary linked against glibc.