{"cve":"CVE-2018-1000027","nvd":{"published":"2018-02-09T23:29:00.870","modified":"2026-06-17T01:32:14.273","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.0","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-476"],"references":["http://www.squid-cache.org/Advisories/SQUID-2018_2.txt","http://www.squid-cache.org/Versions/v3/3.5/changesets/SQUID-2018_2.patch","http://www.squid-cache.org/Versions/v4/changesets/SQUID-2018_2.patch","https://github.com/squid-cache/squid/pull/129/files","https://lists.debian.org/debian-lts-announce/2018/02/msg00001.html"],"products":["canonical:ubuntu_linux","debian:debian_linux","squid-cache:squid"],"source":"nvd","synced_at":"2026-10-19T20:48:34.567387330+00:00"},"epss":{"cve":"CVE-2018-1000027","score":0.12912,"percentile":0.96308,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}