CVE-2021-28662

CVE-2021-28662 is a medium-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 6.5. Its EPSS exploit-prediction score of 72% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-116.

Key facts

Description

An issue was discovered in Squid 4.x before 4.15 and 5.x before 5.0.6. If a remote server sends a certain response header over HTTP or HTTPS, there is a denial of service. This header can plausibly occur in benign network traffic.

Frequently asked questions

What is CVE-2021-28662?
An issue was discovered in Squid 4.x before 4.15 and 5.x before 5.0.6. If a remote server sends a certain response header over HTTP or HTTPS, there is a denial of service. This header can plausibly occur in benign network traffic.
How severe is CVE-2021-28662?
CVE-2021-28662 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-28662 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 72% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28662?
CVE-2021-28662 primarily affects Squid-cache Squid. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-28662?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-28662 published?
CVE-2021-28662 was published on 2021-05-27 and last updated on 2026-06-17.

References

Affected products (4)

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