Squid Web Proxy up to 4.14/5.0.5 HTTP Response denial of service

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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3.6$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic was found in Squid Web Proxy up to 4.14/5.0.5. This impacts an unknown function of the component HTTP Response Handler. The manipulation results in denial of service. This vulnerability is cataloged as CVE-2021-33620. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Squid Web Proxy up to 4.14/5.0.5 (Firewall Software). It has been classified as problematic. Affected is an unknown function of the component HTTP Response Handler. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability.

The weakness was shared 05/29/2021. The advisory is shared for download at github.com. This vulnerability is traded as CVE-2021-33620. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 275771 (Oracle Linux 7 : squid (ELSA-2025-19167)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.15 or 5.0.6 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at squid-cache.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (275771). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.7
VulDB Meta Temp Score: 3.6

VulDB Base Score: 3.7
VulDB Temp Score: 3.6
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 275771
Nessus Name: Oracle Linux 7 : squid (ELSA-2025-19167)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Web Proxy 4.15/5.0.6
Patch: squid-cache.org

Timelineinfo

05/28/2021 🔍
05/29/2021 +1 days 🔍
05/29/2021 +0 days 🔍
11/20/2025 +1636 days 🔍

Sourcesinfo

Vendor: squid-cache.org

Advisory: github.com
Status: Confirmed

CVE: CVE-2021-33620 (🔍)
GCVE (CVE): GCVE-0-2021-33620
GCVE (VulDB): GCVE-100-176064

Entryinfo

Created: 05/29/2021 07:55
Updated: 11/20/2025 02:14
Changes: 05/29/2021 07:55 (40), 06/03/2021 10:07 (5), 06/03/2021 10:13 (1), 11/20/2025 02:14 (16)
Complete: 🔍
Cache ID: 216::103

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

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