# CVE-2018-1000027: squid3: The Squid Software Foundation Squid HTTP Caching Proxy version prior to version 4.0.23 contains a NULL Pointer Derefe...

CVE-2018-1000027 is fixed in 6 products on 1 platform, first by squid 3.5.23-5ubuntu2, released January 28, 2018. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2018-1000027
- Priority: Routine
- CVSS: n/a (Low)
- EPSS: 0.1291
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 28, 2018

## Description

The Squid Software Foundation Squid HTTP Caching Proxy version prior to version 4.0.23 contains a NULL Pointer Dereference vulnerability in HTTP Response X-Forwarded-For header processing that can result in Denial of Service to all clients of the proxy. This attack appear to be exploitable via Remote HTTP server responding with an X-Forwarded-For header to certain types of HTTP request. This vulnerability appears to have been fixed in 4.0.23 and later.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | squid Ubuntu 18.04.6 LTS (bionic) | 3.5.23-5ubuntu2 | [squid 3.5.23-5ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-3.5.23-5ubuntu2.md) | Jan 28, 2018 |
| Linux | squid-cgi Ubuntu 18.04.6 LTS (bionic) | 3.5.23-5ubuntu2 | [squid-cgi 3.5.23-5ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-cgi-3.5.23-5ubuntu2.md) | Jan 28, 2018 |
| Linux | squid-common Ubuntu 18.04.6 LTS (bionic) | 3.5.23-5ubuntu2 | [squid-common 3.5.23-5ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-common-3.5.23-5ubuntu2.md) | Jan 28, 2018 |
| Linux | squid-purge Ubuntu 18.04.6 LTS (bionic) | 3.5.23-5ubuntu2 | [squid-purge 3.5.23-5ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid-purge-3.5.23-5ubuntu2.md) | Jan 28, 2018 |
| Linux | squid3 Ubuntu 18.04.6 LTS (bionic) | 3.5.23-5ubuntu2 | [squid3 3.5.23-5ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squid3-3.5.23-5ubuntu2.md) | Jan 28, 2018 |
| Linux | squidclient Ubuntu 18.04.6 LTS (bionic) | 3.5.23-5ubuntu2 | [squidclient 3.5.23-5ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-squidclient-3.5.23-5ubuntu2.md) | Jan 28, 2018 |

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Data as of 2026-11-07T18:46:35Z 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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