CVE-2026-33526
Publication date 26 March 2026
Last updated 21 October 2026
Ubuntu priority
Description
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| squid | 26.10 stonking |
Not affected
|
| 26.04 LTS resolute |
Not affected
|
|
| 24.04 LTS noble |
Fixed in 6.14-0ubuntu0.24.04.2
|
|
| 22.04 LTS jammy |
Fixed in 5.9-0ubuntu0.22.04.5
|
|
| 20.04 LTS focal |
Fixed in 4.10-1ubuntu1.13+esm3
|
|
| squid3 | 26.10 stonking | Not in release |
| 26.04 LTS resolute | Not in release | |
| 24.04 LTS noble | Not in release | |
| 22.04 LTS jammy | Not in release | |
| 18.04 LTS bionic |
Fixed in 3.5.27-1ubuntu1.14+esm6
|
|
| 16.04 LTS xenial |
Fixed in 3.5.12-1ubuntu7.16+esm7
|
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CVSS version:
Base score
9.2 · Critical
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
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
References
Related Ubuntu Security Notices (USN)
- USN-8157-1
- Squid vulnerabilities
- 8 April 2026
- USN-8941-1
- Squid vulnerabilities
- 20 October 2026