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CVE-2017-18205

24
FAUCET Score

CVE-2017-18205 describes a NULL pointer dereference vulnerability in zsh versions prior to 5.4, specifically when operating in sh compatibility mode and the 'cd' command is invoked without arguments while the HOME environment variable is unset. This flaw carries a high severity CVSS score of 8.1, indicating a critical risk due to its network-exploitable nature, high impact on confidentiality, integrity, and availability, and low attack complexity. Despite its severity, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.4CPE matchmatch criteria
cpe:2.3:a:zsh_project:zsh:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.1HIGH

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
2.09%
Probability of exploitation in next 30 days
EPSS Percentile
79.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0209 is in the 37th percentile among its peer group of 8,918 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: zsh-0:5.0.2-31.el7
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: zsh
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: zsh

Vendor Advisories (1)

redhatCVE-2017-18205Low

zsh: NULL dereference in cd in sh compatibility mode under given circumstances

Jun 13, 2017

References

access.redhat.com / errata/RHSA-2018:3073
security.gentoo.org / glsa/201805-10
sourceforge.net / p/zsh/code/ci/eb783754bdb74377f3cea4ceca9c23a02ea1bf58
PatchThird Party Advisory
usn.ubuntu.com / 3593-1