CVE-2004-0189
Description
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
Exploits
Public proof-of-concept code below. AS-IS, for defenders and authorised testing only.
Exploit-DB
Squid Proxy 2.4/2.5 - NULL URL Character Unauthorized Access
source: https://www.securityfocus.com/bid/9778/info
It has been reported that Squid Proxy may be prone to an unauthorized access vulnerability that may allow remote users to bypass access controls resulting in unauthorized access to attacker-specified resources. The vulnerability presents itself when a URI that is designed to access a specific location with a supplied username, contains '%00' characters. This sequence may be placed as part of the username value prior to the @ symbol in the malicious URI.
Squid Proxy versions 2.0 to 2.5 STABLE4 are reported to be prone to this vulnerability.
http://foo%00@www.example.com/OS impact
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 2.5.5-1 |
| sid | Fixed | 2.5.5-1 |
| forky | Fixed | 2.5.5-1 |
| bullseye | Fixed | 2.5.5-1 |
| bookworm | Fixed | 2.5.5-1 |
References
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.