The "%xx" URL decoding function in Squid 2.5STABLE4 and earlier allows remote attackers to bypass url_regex ACLs via a URL with a NULL ("%00") character, which causes Squid to use only a portion of the requested URL when comparing it against the access control lists.
| Software | From | Fixed in |
|---|---|---|
| squid / squid | 2.1_patch2 | 2.1_patch2.x |
| squid / squid | 2.0_patch2 | 2.0_patch2.x |
| squid / squid | 2.5_stable3 | 2.5_stable3.x |
| squid / squid | 2.4_stable7 | 2.4_stable7.x |
| squid / squid | 2.3_stable5 | 2.3_stable5.x |
| squid / squid | 2.4 | 2.4.x |
| squid / squid | 2.5_stable4 | 2.5_stable4.x |