Affects Windows PowerShell, a ubiquitous enterprise component; RCE via path traversal can enable widespread lateral movement and persistent compromise.
CVE-2026-40400
Relative path traversal in Windows PowerShell enables remote code execution by authorized users.
Is CVE-2026-40400 being exploited?
Not confirmed. CVE-2026-40400 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.87% probability of exploitation in the next 30 days.
How severe is CVE-2026-40400?
CVE-2026-40400 is rated High with a CVSS score of 8.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-40400?
Yes. A fix has been recorded for CVE-2026-40400. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-40400 affect?
CVE-2026-40400 affects Windows PowerShell, PowerShell remoting/WinRM services. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-40400?
Limit/disable PowerShell remoting, enforce least privilege, monitor logs, and apply vendor patch when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
An authorized attacker can exploit relative path traversal to execute arbitrary code remotely over the network, enabling lateral movement and persistence.
Immediate action required
- affected>= 10.0.14393.0 and < 10.0.14393.9339
- affected>= 10.0.17763.0 and < 10.0.17763.9020
- affected>= 10.0.19044.0 and < 10.0.19044.7548
- affected>= 10.0.19045.0 and < 10.0.19045.7548
- affected>= 10.0.26100.0 and < 10.0.26100.8875
- affected>= 10.0.26200.0 and < 10.0.26200.8875
- affected>= 10.0.28000.0 and < 10.0.28000.2525
- affected>= 6.2.9200.0 and < 6.2.9200.26226
- affected>= 6.3.9600.0 and < 6.3.9600.23291
- affected>= 6.3.9600.0 and < 6.3.9600.23291
- affected>= 6.2.9200.0 and < 6.2.9200.26226
- affected>= 10.0.14393.0 and < 10.0.14393.9339
- affected>= 10.0.14393.0 and < 10.0.14393.9339
- affected>= 10.0.17763.0 and < 10.0.17763.9020
- affected>= 10.0.17763.0 and < 10.0.17763.9020
- affected>= 10.0.20348.0 and < 10.0.20348.5386
- affected>= 10.0.26100.0 and < 10.0.26100.33158
- affected>= 10.0.26100.0 and < 10.0.26100.33158
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.