CVE-2021-41611

7.5 HighFix available

An issue was discovered in Squid 5.0.6 through 5.1.x before 5.2. When validating an origin server or peer certificate, Squid may incorrectly classify certain certificates as trusted. This problem allows a remote server to obtain security trust well improperly. This indication of trust may be passed along to clients, allowing access to unsafe or hijacked services.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: None
Availability: None

Exploit likelihood

2.95%Up 2.3 points since Oct 19, 2021

What each source reports

NVD Score used 7.5

Record: CVE-2021-41611
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:P/I:N/A:N
Weakness: CWE-295
Updated: 2026-11-02

CVE List No score

Record: CVE-2021-41611
Updated: 2026-11-02

EUVDEUVD-2021-28625 No score

Record: EUVD-2021-28625
Updated: 2026-11-03

OSVALPINE-CVE-2021-41611 7.5

Record: ALPINE-CVE-2021-41611
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated: 2026-11-02

OSV 7.5

Record: CVE-2021-41611
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated: 2026-11-02

OSVDEBIAN-CVE-2021-41611 7.5

Record: DEBIAN-CVE-2021-41611
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`squid` Alpine:v3.13	5.0.6 up to 5.0.6-r2	5.0.6-r2
`squid` Alpine:v3.14	5.0.6 up to 5.0.6-r2	5.0.6-r2
`squid` Alpine:v3.15	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.16	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.17	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.18	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.19	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.20	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.21	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.22	5.0.6 up to 5.2-r0	5.2-r0

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Affected packages
Package	Affected	Fixed
`squid` Alpine:v3.23	5.0.6 up to 5.2-r0	5.2-r0
`squid` Alpine:v3.24	5.0.6 up to 5.2-r0	5.2-r0
`squid` Debian:12	before 5.2-1	5.2-1
`squid` Debian:13	before 5.2-1	5.2-1
`squid` Debian:14	before 5.2-1	5.2-1

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-41611 is a high vulnerability (CVSS 7.5) in Squid-cache Squid, published October 18, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.95%, the 87th percentile. Fixed in squid 5.0.6-r2.