What is CVE-2018-7548?

CVE-2018-7548 is a critical-severity vulnerability in Zsh, classified under NULL Pointer Dereference. CVSS score: 9.8/10. Published 2018-02-27.

How severe is CVE-2018-7548?

Critical severity. CVSS v3 base score is 9.8 out of 10.

NULL pointer dereference in Zsh

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 modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.025 (84.4th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 84th percentile — 84.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.025 · newest: 0.025 · change: 0.000

Affected products

Zsh
Canonical Ubuntu Linux — versions 17.10

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

References

usn.ubuntu.com/3593-1/ (vendor-advisory, Third Party Advisory)
security.gentoo.org/glsa/201805-10 (vendor-advisory, Third Party Advisory)
sourceforge.net/p/zsh/code/ci/110b13e1090bc31ac1352b28adc2d02b6d25a102 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2018-7548?: CVE-2018-7548 is a critical-severity vulnerability in Zsh, classified under NULL Pointer Dereference. CVSS score: 9.8/10. Published 2018-02-27.
How severe is CVE-2018-7548?: Critical severity. CVSS v3 base score is 9.8 out of 10.