Squid Web Proxy up to 3.x/4.8 URI Scheme input validation

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
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7.2$5k-$25k0.00

A vulnerability classified as critical has been found in Squid Web Proxy up to 3.x/4.8 (Firewall Software). Affected is an unknown code of the component URI Scheme Handler. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as 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. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity is high due to this vulnerability occurring before normal security checks; any remote client that can reach the proxy port can trivially perform the attack via a crafted URI scheme.

The weakness was published 11/26/2019 (Website). The advisory is available at squid-cache.org. This vulnerability is traded as CVE-2019-18676 since 11/04/2019. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 03/05/2025).

The vulnerability scanner Nessus provides a plugin with the ID 222853 (Linux Distros Unpatched Vulnerability : CVE-2019-18676), which helps to determine the existence of the flaw in a target environment.

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

The vulnerability is also documented in the vulnerability database at Tenable (222853). Similar entries are available at VDB-146433, VDB-146432 and VDB-146431.

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.4
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Input validation
CWE: CWE-20
CAPEC: 🔍
ATT&CK: 🔍

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 222853
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2019-18676

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔍

Patch: github.com

Timelineinfo

11/04/2019 🔍
11/26/2019 +22 days 🔍
11/27/2019 +1 days 🔍
03/05/2025 +1925 days 🔍

Sourcesinfo

Vendor: squid-cache.org

Advisory: USN-4213-1
Status: Confirmed

CVE: CVE-2019-18676 (🔍)
See also: 🔍

Entryinfo

Created: 11/27/2019 08:52 AM
Updated: 03/05/2025 08:23 AM
Changes: 11/27/2019 08:52 AM (38), 11/27/2019 08:57 AM (18), 02/28/2024 02:33 PM (4), 03/05/2025 08:23 AM (23)
Complete: 🔍
Cache ID: 18:049:40

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