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CVE-2021-33620

MediumCVSS 6.5 / 10
Published May 28, 2021·Last modified Apr 16, 2026
Affected Components(0)

No affected components available

Description

Squid before 4.15 and 5.x before 5.0.6 allows remote servers to cause a denial of service (affecting availability to all clients) via an HTTP response. The issue trigger is a header that can be expected to exist in HTTP traffic without any malicious intent by the server.

Risk Scores
Base Score
6.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
6.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
79.58%

The exploit probability is very high. The vulnerability is very likely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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