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Fencer Intel
high 8.1

CVE-2017-18205 json

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…

published 2018-02-27 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-9338

cvss
8.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

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.

Patch / fix

  • zsh_project zsh 5.4
  • zsh Debian 14, Debian 13, Debian 12 5.4.1-1

debian advisories DEBIAN-CVE-2017-18205

  • zsh Ubuntu 14.04 LTS 5.0.2-3ubuntu6.1
  • zsh Ubuntu 16.04 LTS 5.1.1-1ubuntu2.1

ubuntu advisories UBUNTU-CVE-2017-18205

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • zsh RHEL 7 5.0.2-31.el7
  • zsh-html RHEL 7 5.0.2-31.el7

red hat advisories RHSA-2018:3073

  • zsh SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 4.3.6-67.9.8.1
  • zsh SLES for SAP 12 SP3, SLES 12 SP3, SLED 12 SP3 5.0.5-6.7.2

suse advisories SUSE-SU-2022:14910-1SUSE-SU-2018:1072-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2017-18205 updated cvss 2.0

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

  • Red Hat Enterprise Linux 5 zsh Red Hat Enterprise Linux 6 zsh, zsh-html
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux Client (v. 7) zsh 5.0.2-31.el7 Red Hat Enterprise Linux Client Optional (v. 7) zsh-html 5.0.2-31.el7 Red Hat Enterprise Linux ComputeNode (v. 7) zsh 5.0.2-31.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) zsh-html 5.0.2-31.el7 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) zsh 5.0.2-31.el7 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) zsh-html 5.0.2-31.el7
    +4 more products
    Red Hat Enterprise Linux Server (v. 7) zsh 5.0.2-31.el7 Red Hat Enterprise Linux Server Optional (v. 7) zsh-html 5.0.2-31.el7 Red Hat Enterprise Linux Workstation (v. 7) zsh 5.0.2-31.el7 Red Hat Enterprise Linux Workstation Optional (v. 7) zsh-html 5.0.2-31.el7
    fixed: vendor fix RHSA-2018:3073
  • Red Hat Enterprise Linux 8 zsh, zsh-html
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.04% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.