CVE-2018-7549 [High] | Input Validation Bypass in Zsh

CVE-2018-7549 is rated Moderate Risk (45.5/100): CVSS High severity, with low exploitation likelihood (EPSS 0.22%). Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-13	0.32%	0.22%	-0.10%
2	2026-01-27	0.19%	0.32%	+0.13%
3	2025-12-08	—	0.19%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-13

0.32%

0.22%

-0.10%

2026-01-27

0.19%

0.32%

+0.13%

2025-12-08

—

0.19%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.0	HIGH	`CVSS:3.0/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

3.0

HIGH

CVSS:3.0/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-2018-7549

vendor	priority	summary	link
`alpine`	high	CVE-2018-7549: 1 source package rows (zsh); 5 state rows across 5 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 5.	https://security.alpinelinux.org/vuln/CVE-2018-7549
`debian`	unimportant	CVE-2018-7549 unimportant priority: Debian including 1 source packages (zsh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2018-7549
`gentoo`	normal	CVE-2018-7549: 1 GLSA(s) (201805-10), 1 atom(s) (app-shells/zsh); latest impact normal.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2018-7549
`redhat`	low	—	https://access.redhat.com/security/cve/CVE-2018-7549
`suse`	low	CVE-2018-7549 severity low: SUSE including 5 source package names (zsh, zsh-4.3.6-67.9.8.1, zsh-5.0.2-31.el7, zsh-5.0.5-6.7.2, zsh-html-5.0.2-31.el7), 50 product×package rows across 49 product lines (Image SLES12-SP5-Azure-BYOS, Image SLES12-SP5-Azure-Basic-On-Demand, … (49 product lines)): Fixed 33, Known Not Affected 17.	https://www.suse.com/security/cve/CVE-2018-7549/
`ubuntu`	medium	CVE-2018-7549 medium priority: Ubuntu including 1 source packages (zsh), 4 status rows across 4 suites (artful, trusty, upstream, xenial): released 3, needs-triage 1.	https://ubuntu.com/security/CVE-2018-7549

Affected software / configurations for CVE-2018-7549

Vendor	Product	Version	Raw CPE
zsh	zsh	<= 5.4.2	cpe:2.3:a:zsh:zsh::::::::
redhat	enterprise_linux_desktop	7.0	cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:::::::*
redhat	enterprise_linux_server	7.0	cpe:2.3:o:redhat:enterprise_linux_server:7.0:::::::*
redhat	enterprise_linux_workstation	7.0	cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:::::::*
canonical	ubuntu_linux	14.04	cpe:2.3:o:canonical:ubuntu_linux:14.04::::lts:::
canonical	ubuntu_linux	16.04	cpe:2.3:o:canonical:ubuntu_linux:16.04::::lts:::
canonical	ubuntu_linux	17.10	cpe:2.3:o:canonical:ubuntu_linux:17.10:::::::*

References for CVE-2018-7549

URL	Tags
https://access.redhat.com/errata/RHSA-2018:3073	Third Party Advisory
https://security.gentoo.org/glsa/201805-10	Third Party Advisory
https://sourceforge.net/p/zsh/code/ci/c2cc8b0fbefc9868fa83537f5b6d90fc1ec438dd	Patch Third Party Advisory
https://usn.ubuntu.com/3593-1/	Third Party Advisory

URL

CVE-2018-7549

Exploit prediction scoring system (EPSS) score for CVE-2018-7549

Common vulnerability scoring system (CVSS) metrics for CVE-2018-7549

Weakness enumeration for CVE-2018-7549

OS Trackers for CVE-2018-7549

Affected software / configurations for CVE-2018-7549

References for CVE-2018-7549