Use After Free in Squid-Cache Squid
CVE-2026-33526
Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. Version 7.5 contains a patch.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.089 (95.2th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 95th percentile — 95.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.089 · newest: 0.089 · change: 0.000
Affected products
- Squid-Cache Squid — versions < 7.5
Weakness classification (CWE)
References
- github.com/squid-cache/squid/security/advisories/GHSA-hpfx-h48q-gvwg (Vendor Advisory)
- github.com/squid-cache/squid/commit/8a7d42f9d44befb8fcbbb619505587c8de6a1e91 (Patch)
- af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-33526?
- CVE-2026-33526 is a high-severity vulnerability in Squid-Cache Squid, classified under Use After Free. CVSS score: 7.5/10. Published 2026-03-26.
- How severe is CVE-2026-33526?
- High severity. CVSS v3 base score is 7.5 out of 10.