Squid Web Proxy up to 4.7/5.0 Cache input validation

Summaryinfo

A vulnerability labeled as problematic has been found in Squid Web Proxy up to 4.7/5.0. The impacted element is an unknown function of the component Cache Handler. Executing a manipulation can lead to input validation. This vulnerability appears as CVE-2019-12520. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability has been found in Squid Web Proxy up to 4.7/5.0 (Firewall Software) and classified as problematic. This vulnerability affects an unknown part of the component Cache Handler. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality. CVE summarizes:

An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request. If found, it servers the request. The absolute URL can include the decoded UserInfo (username and password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to provide a username that has special characters to delimit the domain, and treat the rest of the URL as a path or query string. An attacker could first make a request to their domain using an encoded username, then when a request for the target domain comes in that decodes to the exact URL, it will serve the attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows an attacker to gain access to features that only reverse proxies can use, such as ESI.

The weakness was presented 04/15/2020. This vulnerability was named CVE-2019-12520 since 06/02/2019. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 04/16/2020).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

See VDB-153691, VDB-153690, VDB-153689 and VDB-153687 for similar entries. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Firewall Software

Vendor

• Squid

Name

• Web Proxy

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 5.0

License

• open-source

Website

• Vendor: http://www.squid-cache.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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