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MEDIUM

CVE-2021-31807

CVSS v3

6.5

MEDIUM

EPSS Score

15.6 %

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-2021-31807 Red Hat Product Security30 products fixed · 8 known affected

    squid: incorrect memory management in HTTP Range header

    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. An integer overflow problem allows a remote server to achieve Denial of Service when delivering responses to HTTP Range requests. The issue trigger is a header that can be expected to exist in HTTP traffic without any malicious intent.

Technical details

Published
2021-06-08

Frequently asked questions

What is CVE-2021-31807?

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. An integer overflow problem allows a remote server to achieve Denial of Service when delivering responses to HTTP Range requests. The issue trigger is a header that can be expected to exist in HTTP traffic without any malicious intent.

Is CVE-2021-31807 actively exploited?

Active exploitation of CVE-2021-31807 has not been confirmed. Its EPSS score was 15.6% on 2026-10-20, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-31807?

CVE-2021-31807 has a CVSS v3 base score of 6.5 (MEDIUM severity).

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