CVE-2020-14058 [High] | Denial of Service in Squid

An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized error values are mapped to NULL, but later code expects that each error value is mapped to a valid error string.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	1.54%	2.61%	+1.06%
2	2026-06-08	0.60%	1.54%	+0.94%
3	2026-06-07	—	0.60%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

1.54%

2.61%

+1.06%

2026-06-08

0.60%

1.54%

+0.94%

2026-06-07

—

0.60%

—

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]
5.0	2.0	MEDIUM	`AV:N/AC:L/Au:N/C:N/I:N/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:P) Partial availability impact.	10.0	2.9	[email protected]

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]

5.0

2.0

MEDIUM

AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

2.9

[email protected]

OS Trackers for CVE-2020-14058

vendor	priority	summary	link
`alpine`	high	CVE-2020-14058: 1 source package rows (squid); 20 state rows across 5 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 20.	https://security.alpinelinux.org/vuln/CVE-2020-14058
`debian`	unimportant	CVE-2020-14058 unimportant 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-2020-14058
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2020-14058
`suse`	high	—	https://www.suse.com/security/cve/CVE-2020-14058/
`ubuntu`	medium	CVE-2020-14058 medium priority: Ubuntu including 2 source packages (squid, squid3), 12 status rows across 6 suites (bionic, eoan, focal, trusty, upstream, xenial): DNE 6, not-affected 4, needs-triage 2.	https://ubuntu.com/security/CVE-2020-14058

Affected software / configurations for CVE-2020-14058

Vendor	Product	Version	Raw CPE
squid-cache	squid	>= 3.1, <= 3.5.28	cpe:2.3:a:squid-cache:squid::::::::
squid-cache	squid	>= 4.0, < 4.12	cpe:2.3:a:squid-cache:squid::::::::
squid-cache	squid	>= 5.0, < 5.0.3	cpe:2.3:a:squid-cache:squid::::::::
fedoraproject	fedora	31	cpe:2.3:o:fedoraproject:fedora:31:::::::*
netapp	cloud_manager	—	cpe:2.3:a:netapp:cloud_manager:-:::::::*

References for CVE-2020-14058

URL	Tags
http://www.squid-cache.org/Advisories/SQUID-2020_6.txt	Vendor Advisory
http://www.squid-cache.org/Versions/v4/changesets/squid-4-93f5fda134a2a010b84ffedbe833d670e63ba4be.patch	Patch Vendor Advisory
http://www.squid-cache.org/Versions/v5/changesets/squid-5-c6d1a4f6a2cbebceebc8a3fcd8f539ceb7b7f723.patch	Patch Vendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3RG5FGSTCAYVIJPJHIY3MRZ7NFT6HDO7/
https://security.netapp.com/advisory/ntap-20210312-0001/	Third Party Advisory

URL

CVE-2020-14058

Exploit prediction scoring system (EPSS) score for CVE-2020-14058

Common vulnerability scoring system (CVSS) metrics for CVE-2020-14058

Weakness enumeration for CVE-2020-14058

OS Trackers for CVE-2020-14058

Affected software / configurations for CVE-2020-14058

References for CVE-2020-14058