# CVE-2021-31808: squid: An issue was discovered in Squid before 4.15 and 5.x before 5.0.6 CVE-2021-31808 is fixed in 9 products on 1 platform, first by squid 3.5.27-1ubuntu1.11, released May 28, 2021. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2021-31808 - Priority: Routine - CVSS: 6.5 (Medium) - EPSS: 0.0534 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 27, 2021 ## Description An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due toan input-validation bug, it is vulnerable to a Denial of Service attack(against all clients using the proxy). A client sends an HTTP Range requestto trigger this. ## 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 18.04.6 LTS (bionic) | 3.5.27-1ubuntu1.11 | [squid 3.5.27-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-3.5.27-1ubuntu1.11.md) | May 28, 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 Ubuntu 24.10 (oracular) | 4.13-10ubuntu1 | [squid 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-squid-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid Ubuntu 25.04 (plucky) | 4.13-10ubuntu1 | [squid 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-squid-4.13-10ubuntu1.md) | Jan 16, 2026 | | 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 18.04.6 LTS (bionic) | 3.5.27-1ubuntu1.11 | [squid-cgi 3.5.27-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-cgi-3.5.27-1ubuntu1.11.md) | May 28, 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-cgi Ubuntu 24.10 (oracular) | 4.13-10ubuntu1 | [squid-cgi 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-squid-cgi-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid-cgi Ubuntu 25.04 (plucky) | 4.13-10ubuntu1 | [squid-cgi 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-squid-cgi-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid-common Ubuntu 18.04.6 LTS (bionic) | 3.5.27-1ubuntu1.11 | [squid-common 3.5.27-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-common-3.5.27-1ubuntu1.11.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-common Ubuntu 24.10 (oracular) | 4.13-10ubuntu1 | [squid-common 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-squid-common-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid-common Ubuntu 25.04 (plucky) | 4.13-10ubuntu1 | [squid-common 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-squid-common-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid-openssl Ubuntu 24.10 (oracular) | 4.13-10ubuntu1 | [squid-openssl 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-squid-openssl-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid-openssl Ubuntu 25.04 (plucky) | 4.13-10ubuntu1 | [squid-openssl 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-squid-openssl-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid-purge Ubuntu 18.04.6 LTS (bionic) | 3.5.27-1ubuntu1.11 | [squid-purge 3.5.27-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-purge-3.5.27-1ubuntu1.11.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 | squid-purge Ubuntu 24.10 (oracular) | 4.13-10ubuntu1 | [squid-purge 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-squid-purge-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid-purge Ubuntu 25.04 (plucky) | 4.13-10ubuntu1 | [squid-purge 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-squid-purge-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squid3 Ubuntu 18.04.6 LTS (bionic) | 3.5.27-1ubuntu1.11 | [squid3 3.5.27-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid3-3.5.27-1ubuntu1.11.md) | May 28, 2021 | | Linux | squidclient Ubuntu 18.04.6 LTS (bionic) | 3.5.27-1ubuntu1.11 | [squidclient 3.5.27-1ubuntu1.11](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squidclient-3.5.27-1ubuntu1.11.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 | | Linux | squidclient Ubuntu 24.10 (oracular) | 4.13-10ubuntu1 | [squidclient 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-squidclient-4.13-10ubuntu1.md) | Jan 16, 2026 | | Linux | squidclient Ubuntu 25.04 (plucky) | 4.13-10ubuntu1 | [squidclient 4.13-10ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-squidclient-4.13-10ubuntu1.md) | Jan 16, 2026 | --- Data as of 2026-11-09T07:25:28Z 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 Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.