The Linux kernel 2.4.20 and earlier, and 2.5.x, when running on x86 systems, allows local users to cause a denial of service (hang) via the emulation mode, which does not properly clear TF and NT EFLAGs.
Squid before 2.3STABLE5 in HTTP accelerator mode does not enable access control lists (ACLs) when the httpd_accel_host and http_accel_with_proxy off settings are used, which allows attackers to bypass the ACLs and conduct unauthorized activities such as port scanning.
When using the LD_PRELOAD environmental variable in SUID or SGID applications, glibc does not verify that preloaded libraries in /etc/ld.so.cache are also SUID/SGID, which could allow a local user to overwrite arbitrary files by loading a library from /lib or /usr/lib.