CVE-2023-46728 | SQUID-2021:8 Denial of Service in Gopher gateway

Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Due to a NULL pointer dereference bug Squid is vulnerable to a Denial of Service attack against Squid's Gopher gateway. The gopher protocol is always available and enabled in Squid prior to Squid 6.0.1. Responses triggering this bug are possible to be received from any gopher server, even those without malicious intent. Gopher support has been removed in Squid version 6.0.1. Users are advised to upgrade. Users unable to upgrade should reject all gopher URL requests.

Published: 2023-11-06 Last update: 2025-11-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-46728 is rated High Risk (66/100): CVSS High severity, with high exploitation likelihood (EPSS 5.96%, 92th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +3.69% 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-2023-46728

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 2.26% 5.96% +3.69%
2 2026-02-23 1.88% 2.26% +0.39%
3 2025-12-28 — 1.88% —

Full EPSS history (27 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-46728

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
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]
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-2023-46728

OS Trackers for CVE-2023-46728

vendor priority summary link
alpine high CVE-2023-46728: 1 source package rows (squid); 52 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 0, open 52. https://security.alpinelinux.org/vuln/CVE-2023-46728
debian not yet assigned CVE-2023-46728 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-2023-46728
redhat high — https://access.redhat.com/security/cve/CVE-2023-46728
suse high — https://www.suse.com/security/cve/CVE-2023-46728/
ubuntu medium CVE-2023-46728 medium priority: Ubuntu including 2 source packages (squid, squid3), 16 status rows across 8 suites (bionic, focal, jammy, lunar, mantic, trusty, upstream, xenial): released 6, DNE 4, ignored 4, needs-triage 1, not-affected 1. https://ubuntu.com/security/CVE-2023-46728

Affected software / configurations for CVE-2023-46728

Vendor Product Version Raw CPE
squid-cache squid < 6.0.1 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*

References for CVE-2023-46728

cvelogic Threat Intelligence