Actively exploitedKnown ransomware use

CVE-2023-38831 RARLAB WinRAR Code Execution Vulnerability

RARLAB WinRAR contains an unspecified vulnerability that allows an attacker to execute code when a user attempts to view a benign file within a ZIP archive.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment

CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 24 Aug 2023.
CISA lists it as known to be used in ransomware campaigns.
Rated High severity (CVSS 7.8, scored by CISA).
It has been in the catalogue for 1,170 days. Systems still unpatched now have almost certainly been scanned for it.

The Vulnerability

What It Is

RARLAB WinRAR before 6.23 allows attackers to execute arbitrary code when a user attempts to view a benign file within a ZIP archive. The issue occurs because a ZIP archive may include a benign file (such as an ordinary .JPG file) and also a folder that has the same name as the benign file, and the contents of the folder (which may include executable content) are processed during an attempt to access only the benign file. This was exploited in the wild in April through October 2023.

From Watch to Action

What To Do Now

1
Find it
Search your asset inventory and external attack surface for RARLAB WinRAR. Include cloud images, appliances and anything a supplier runs for you.
Attack Surface Management
2
Fix it
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Vulnerability Management
3
Hunt for compromise
If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.
Incident Response
4
Prove it is fixed
Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.
Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 14 Sep 2023 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited RARLAB Flaws

All 5 exploited RARLAB vulnerabilities

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2023-38831 and every other exploited flaw on the list.

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Evidence

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CLOUD SECURITY

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FOR VENDORS

CVE-2023-38831 RARLAB WinRAR Code Execution Vulnerability

Should You Worry?

What It Is

What To Do Now

Find it

Fix it

Hunt for compromise

Prove it is fixed

Vendor Advisories

The Compliance Clock

More Exploited RARLAB Flaws

Not Sure If You Are Exposed?

Sources