# CVE-2021-28662: squid: An issue was discovered in Squid 4.x before 4.15 and 5.x before 5.0.6

CVE-2021-28662 is fixed in 7 products on 1 platform, first by squid 4.10-1ubuntu1.4, released May 28, 2021. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-28662
- Priority: Routine
- CVSS: 6.5 (Medium)
- EPSS: 0.7176
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 27, 2021

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libecap RHEL 8 | 0:1.0.1-2.module+el8.1.0+4044+36416a77 | [RHSA-2021:4292](https://patchblox.com/security/data/fix/linux/rhsa-2021-4292.md) | Nov 9, 2021 |
| Linux | libecap ol 8 | 0:1.0.1-2.module+el8.3.0+7819+eb7d4ef6 | [ELSA-2021-4292](https://patchblox.com/security/data/fix/linux/elsa-2021-4292.md) | Nov 16, 2021 |
| Linux | libecap-devel RHEL 8 | 0:1.0.1-2.module+el8.1.0+4044+36416a77 | [RHSA-2021:4292](https://patchblox.com/security/data/fix/linux/rhsa-2021-4292.md) | Nov 9, 2021 |
| Linux | libecap-devel ol 8 | 0:1.0.1-2.module+el8.3.0+7819+eb7d4ef6 | [ELSA-2021-4292](https://patchblox.com/security/data/fix/linux/elsa-2021-4292.md) | Nov 16, 2021 |
| Linux | squid RHEL 8 | 7:4.15-1.module+el8.5.0+11469+24c223d9 | [RHSA-2021:4292](https://patchblox.com/security/data/fix/linux/rhsa-2021-4292.md) | Nov 9, 2021 |
| Linux | squid Ubuntu 20.04 LTS (focal) | 4.10-1ubuntu1.4 | [squid 4.10-1ubuntu1.4](https://patchblox.com/security/data/fix/linux/ubuntu-focal-squid-4.10-1ubuntu1.4.md) | May 28, 2021 |
| Linux | squid ol 8 | 7:4.15-1.module+el8.5.0+20327+24c223d9 | [ELSA-2021-4292](https://patchblox.com/security/data/fix/linux/elsa-2021-4292.md) | Nov 16, 2021 |
| Linux | squid-cgi Ubuntu 20.04 LTS (focal) | 4.10-1ubuntu1.4 | [squid-cgi 4.10-1ubuntu1.4](https://patchblox.com/security/data/fix/linux/ubuntu-focal-squid-cgi-4.10-1ubuntu1.4.md) | May 28, 2021 |
| Linux | squid-common Ubuntu 20.04 LTS (focal) | 4.10-1ubuntu1.4 | [squid-common 4.10-1ubuntu1.4](https://patchblox.com/security/data/fix/linux/ubuntu-focal-squid-common-4.10-1ubuntu1.4.md) | May 28, 2021 |
| Linux | squid-purge Ubuntu 20.04 LTS (focal) | 4.10-1ubuntu1.4 | [squid-purge 4.10-1ubuntu1.4](https://patchblox.com/security/data/fix/linux/ubuntu-focal-squid-purge-4.10-1ubuntu1.4.md) | May 28, 2021 |
| Linux | squidclient Ubuntu 20.04 LTS (focal) | 4.10-1ubuntu1.4 | [squidclient 4.10-1ubuntu1.4](https://patchblox.com/security/data/fix/linux/ubuntu-focal-squidclient-4.10-1ubuntu1.4.md) | May 28, 2021 |

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Data as of 2026-11-11T01:43:54Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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