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MEDIUM

CVE-2021-28652

CVSS v3

4.9

MEDIUM

EPSS Score

4.3 %

exploit probability, as of 2026-10-20

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • libecapAlmaLinux:8all versions · fixed in 1.0.1-2.module_el8.6.0+2741+01592ae8and 1 other package
  • squidAlmaLinux:8all versions · fixed in 7:4.15-3.module_el8.6.0+3010+383bc947.1

Vendor advisories

  • CVE-2021-28652 Red Hat Product Security30 products fixed · 8 known affected

    squid: denial of service issue in Cache Manager

    squid as a component of Red Hat Enterprise Linux 6 · squid.src as a component of Red Hat Enterprise Linux 6 · squid34 as a component of Red Hat Enterprise Linux 6

  • RHSA-2021:4292 Red Hat Product Security30 products fixed

    Red Hat Security Advisory: squid:4 security, bug fix, and enhancement update

Full record on NVD

Description

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to incorrect parser validation, it allows a Denial of Service attack against the Cache Manager API. This allows a trusted client to trigger memory leaks that. over time, lead to a Denial of Service via an unspecified short query string. This attack is limited to clients with Cache Manager API access privilege.

Technical details

Published
2021-05-27

Frequently asked questions

What is CVE-2021-28652?

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to incorrect parser validation, it allows a Denial of Service attack against the Cache Manager API. This allows a trusted client to trigger memory leaks that. over time, lead to a Denial of Service via an unspecified short query string. This attack is limited to clients with Cache Manager API access privilege.

Is CVE-2021-28652 actively exploited?

Active exploitation of CVE-2021-28652 has not been confirmed. Its EPSS score was 4.3% on 2026-10-20, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-28652?

CVE-2021-28652 has a CVSS v3 base score of 4.9 (MEDIUM severity).

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