How severe is CVE-2018-7548?

CVE-2018-7548 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-7548 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-7548?

CVE-2018-7548 primarily affects Zsh. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-7548?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2018-7548 published?

CVE-2018-7548 was published on 2018-02-27 and last updated on 2026-06-17.

CVE-2018-7548

CVE-2018-7548 is a critical-severity vulnerability in Zsh with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 3% (83rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Zsh
Published: 2018-02-27
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is 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.
How severe is CVE-2018-7548?: CVE-2018-7548 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-7548 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-7548?: CVE-2018-7548 primarily affects Zsh. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-7548?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2018-7548 published?: CVE-2018-7548 was published on 2018-02-27 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:zsh:zsh:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*

More vulnerabilities in Zsh

CVE-2018-13259 — Critical (CVSS 9.8): An issue was discovered in zsh before 5.6. Shebang lines exceeding 64 characters were truncated, potentially leading to…
CVE-2018-0502 — Critical (CVSS 9.8): An issue was discovered in zsh before 5.6. The beginning of a #! script file was mishandled, potentially leading to an…
CVE-2017-18206 — Critical (CVSS 9.8): In utils.c in zsh before 5.4, symlink expansion had a buffer overflow.
CVE-2016-10714 — Critical (CVSS 9.8): In zsh before 5.3, an off-by-one error resulted in undersized buffers that were intended to support PATH_MAX characters.
CVE-2014-10071 — Critical (CVSS 9.8): In exec.c in zsh before 5.0.7, there is a buffer overflow for very long fds in the ">& fd" syntax.
CVE-2021-45444 — High (CVSS 7.8): In zsh before 5.8.1, an attacker can achieve code execution if they control a command output inside the prompt, as…

All CVEs affecting Zsh →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

CVE-2022-36648 — Critical (CVSS 10.0): The hardware emulation in the of_dpa_cmd_add_l2_flood of rocker device model in QEMU, as used in 7.0.0 and earlier,…
CVE-2020-14500 — Critical (CVSS 10.0): Secomea GateManager all versions prior to 9.2c, An attacker can send a negative value and overwrite arbitrary data.
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2026-46195 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: validate dacloffset before building…
CVE-2026-31657 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by…
CVE-2026-31436 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: fix possible wrong descriptor…

Browse all CWE-476 (NULL Pointer Dereference) vulnerabilities →