CVE-2023-46724 | SQUID-2023:4 Denial of Service in SSL Certificate validation

Squid is a caching proxy for the Web. Due to an Improper Validation of Specified Index bug, Squid versions 3.3.0.1 through 5.9 and 6.0 prior to 6.4 compiled using `--with-openssl` are vulnerable to a Denial of Service attack against SSL Certificate validation. This problem allows a remote server to perform Denial of Service against Squid Proxy by initiating a TLS Handshake with a specially crafted SSL Certificate in a server certificate chain. This attack is limited to HTTPS and SSL-Bump. This bug is fixed in Squid version 6.4. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. Those who you use a prepackaged version of Squid should refer to the package vendor for availability information on updated packages.

Published: 2023-11-01 Last update: 2025-02-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-46724 is rated High Risk (69.3/100): CVSS High severity, with medium exploitation likelihood (EPSS 4.01%). EPSS rose +3.64% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-46724

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.37% 4.01% +3.64%
2 2025-12-28 0.60% 0.37% -0.23%
3 2025-12-27 — 0.60% —

Full EPSS history (31 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-46724

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.0 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-46724

OS Trackers for CVE-2023-46724

vendor priority summary link
alpine — CVE-2023-46724: 1 source package rows (squid); 62 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 5, open 57. https://security.alpinelinux.org/vuln/CVE-2023-46724
debian not yet assigned CVE-2023-46724 not yet assigned priority: Debian including 1 source packages (squid), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-46724
redhat high — https://access.redhat.com/security/cve/CVE-2023-46724
suse high — https://www.suse.com/security/cve/CVE-2023-46724/
ubuntu medium CVE-2023-46724 medium priority: Ubuntu including 2 source packages (squid, squid3), 24 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 8, released 7, ignored 4, needs-triage 4, not-affected 1. https://ubuntu.com/security/CVE-2023-46724

Affected software / configurations for CVE-2023-46724

Vendor Product Version Raw CPE
squid-cache squid >= 3.3.0.1, < 6.4 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*

References for CVE-2023-46724

cvelogic Threat Intelligence