zsh through version 5.4.2 is vulnerable to a stack-based buffer overflow in the exec.c:hashcmd() function.
zsh through version 5.4.2 is vulnerable to a stack-based buffer overflow in the exec.c:hashcmd() function. A local attacker could exploit this to cause a denial of service.
- Published
- Mar 9, 2018
- Updated
- Jun 16, 2026
- EPSS
- 0.4% · 35th percentile
- CWE
- CWE-121
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Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| zsh | zsh | cpe:2.3:a:zsh:zsh |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| canonical | ubuntu linux | cpe:2.3:o:canonical:ubuntu_linux |
| redhat | enterprise linux desktop | cpe:2.3:o:redhat:enterprise_linux_desktop |
| redhat | enterprise linux server | cpe:2.3:o:redhat:enterprise_linux_server |
| redhat | enterprise linux workstation | cpe:2.3:o:redhat:enterprise_linux_workstation |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- canonical ubuntu linux14.04
- canonical ubuntu linux16.04
- canonical ubuntu linux17.10
- debian debian linux7.0
- redhat enterprise linux desktop7.0
- redhat enterprise linux server7.0
- redhat enterprise linux workstation7.0
- zsh zshup to 5.4.2 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.
zsh zsh
- 5.4.2affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | zsh | before 5.4.2-r1 | 5.4.2-r1 |
| Alpine:v3.4 | zsh | before 5.2-r2 | 5.2-r2 |
| Alpine:v3.5 | zsh | before 5.2-r4 | 5.2-r4 |
| Alpine:v3.6 | zsh | before 5.3.1-r1 | 5.3.1-r1 |
| Debian:12 | zsh | before 5.4.2-4 | 5.4.2-4 |
| Debian:7 | zsh | before 4.3.17-1+deb7u2 | 4.3.17-1+deb7u2 |
| Debian:9 | zsh | before 5.3.1-4+deb9u1 | 5.3.1-4+deb9u1 |
| openSUSE:Tumbleweed | zsh | before 5.8-7.7 | 5.8-7.7 |
| Red Hat:enterprise_linux:7::client | zsh | before 0:5.0.2-31.el7 | 0:5.0.2-31.el7 |
| Red Hat:enterprise_linux:7::client | zsh-debuginfo | before 0:5.0.2-31.el7 | 0:5.0.2-31.el7 |
| Red Hat:enterprise_linux:7::client | zsh-html | before 0:5.0.2-31.el7 | 0:5.0.2-31.el7 |
| SUSE:Linux Enterprise Desktop 12 SP3 | zsh | before 5.0.5-6.7.2 | 5.0.5-6.7.2 |
| SUSE:Linux Enterprise Module for Basesystem 15 | zsh | before 5.5-3.3.15 | 5.5-3.3.15 |
| SUSE:Linux Enterprise Point of Sale 11 SP3 | zsh | before 4.3.6-67.9.8.1 | 4.3.6-67.9.8.1 |
Same product
zsh: all recordsOther highest-scoring records for the same primary product.
- CVE-2018-13259An issue was discovered in zsh before 5.6.40Plan
- CVE-2018-0502An issue was discovered in zsh before 5.6.40Plan
- CVE-2018-7548In subst.c in zsh through 5.4.2, there is a NULL pointer dereference when using ${(PA)...} on an empty array result.40Plan
- CVE-2017-18206In utils.c in zsh before 5.4, symlink expansion had a buffer overflow.40Plan
- CVE-2016-10714In zsh before 5.3, an off-by-one error resulted in undersized buffers that were intended to support PATH_MAX characters.40Plan
- CVE-2014-10071In exec.c in zsh before 5.0.7, there is a buffer overflow for very long fds in the ">& fd" syntax.40Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| alpine:zsh | 5.4.2-r1 · Alpine:v3.10 | Package registry (OSV) |
| debian:zsh | 5.4.2-4 · Debian:12 | Package registry (OSV) |
| opensuse:zsh | 5.8-7.7 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:zsh | 0:5.0.2-31.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:zsh-debuginfo | 0:5.0.2-31.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:zsh-html | 0:5.0.2-31.el7 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| suse:zsh | 5.0.5-6.7.2 · SUSE:Linux Enterprise Desktop 12 SP3 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-121 · Stack-based Buffer OverflowCVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- www.securityfocus.com/bid/103359
- access.redhat.com/errata/RHSA-2018:3073
- bugzilla.redhat.com/show_bug.cgi?id=1553531
- lists.debian.org/debian-lts-announce/2018/03/msg00038.html
- lists.debian.org/debian-lts-announce/2020/12/msg00000.html
- security.gentoo.org/glsa/201805-10
- usn.ubuntu.com/3608-1/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.