CVE-2018-7548

In subst.c in zsh through 5.4.2, there is a NULL pointer dereference when using ${(PA)...} on an empty array result.

Published: 2018-02-27 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-7548 is rated High Risk (70.7/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 2.63%). EPSS rose +2.26% 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-2018-7548

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% 2.63% +2.26%
2 2025-12-08 0.21% 0.37% +0.16%
3 2025-11-21 — 0.21% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-7548

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/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:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2018-7548

OS Trackers for CVE-2018-7548

vendor priority summary link
alpine critical CVE-2018-7548: 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-2018-7548
debian unimportant CVE-2018-7548 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-2018-7548
gentoo normal CVE-2018-7548: 1 GLSA(s) (201805-10), 1 atom(s) (app-shells/zsh); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2018-7548
redhat low — https://access.redhat.com/security/cve/CVE-2018-7548
ubuntu medium CVE-2018-7548 medium priority: Ubuntu including 1 source packages (zsh), 4 status rows across 4 suites (artful, trusty, upstream, xenial): DNE 1, needs-triage 1, not-affected 1, released 1. https://ubuntu.com/security/CVE-2018-7548

Affected software / configurations for CVE-2018-7548

Vendor Product Version Raw CPE
zsh zsh <= 5.4.2 cpe:2.3:a:zsh:zsh:*:*:*:*:*:*:*:*
canonical ubuntu_linux 17.10 cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*

References for CVE-2018-7548

cvelogic Threat Intelligence