CVE-2017-18205

In builtin.c in zsh before 5.4, when sh compatibility mode is used, there is a NULL pointer dereference during processing of the cd command with no argument if HOME is not set.

Published: 2018-02-27 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2017-18205 is rated Moderate Risk (57.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.67%). Review affected assets and schedule 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-2017-18205

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 2026-02-01 0.51% 0.67% +0.16%
2 2026-01-27 0.76% 0.51% -0.24%
3 2025-12-08 — 0.76% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2017-18205

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.1 3.0 HIGH
CVSS:3.0/AV:N/AC:H/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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.
 2.2 5.9 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/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:M)
Exploitation needs some favorable conditions, but not exceptional ones.
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.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2017-18205

OS Trackers for CVE-2017-18205

vendor priority summary link
debian unimportant CVE-2017-18205 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-2017-18205
gentoo normal CVE-2017-18205: 1 GLSA(s) (201805-10), 1 atom(s) (app-shells/zsh); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2017-18205
redhat low — https://access.redhat.com/security/cve/CVE-2017-18205
suse low CVE-2017-18205 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), 51 product×package rows across 50 product lines (Image SLES12-SP5-Azure-BYOS, Image SLES12-SP5-Azure-Basic-On-Demand, … (50 product lines)): Fixed 33, Known Not Affected 18. https://www.suse.com/security/cve/CVE-2017-18205/
ubuntu medium CVE-2017-18205 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-2017-18205

Affected software / configurations for CVE-2017-18205

Vendor Product Version Raw CPE
zsh_project zsh < 5.4 cpe:2.3:a:zsh_project:zsh:*:*:*:*:*:*:*:*

References for CVE-2017-18205

cvelogic Threat Intelligence