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Fencer Vulns
high 7.8

CVE-2023-38831 kev+ ransomware in the critical feed json

RARLAB WinRAR before 6.23 allows attackers to execute arbitrary code when a user attempts to view a benign file within a ZIP archive.

published 2023-08-23 3 y ago modified 2026-08-05 3 mo ago also EUVD-2023-42604

cvss
7.8
version 3.1, CNA
cisa kev
Exploited
added 2023-08-24, used in ransomware
epss
99.8%
EPSS 99.8% chance of exploitation in 30 days, percentile 99.9%
public exploits
1
Metasploit

Summary

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.

Patch / fix

cisa required action Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

  • rarlab winrar 6.23

Timeline

  1. Found exploited as a 0-day (Project Zero)
  2. 0-day patched (Project Zero)
  3. Published
  4. CISA SSVC: exploitation active
  5. First public exploit (Metasploit exploit/windows/fileformat/winrar_cve_2023_38831)
  6. Added to CISA KEV
  7. CISA patch deadline

Known exploited

Added
3 y ago
Patch by
2023-09-14 (3 y ago)
Ransomware
Known to be used in ransomware campaigns
Required action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Vendor, product
RARLAB, WinRAR
CISA name
RARLAB WinRAR Code Execution Vulnerability

Zero-day

Detected in real attacks while still unknown to the vendor and the public, per Google Project Zero's 0day In-the-Wild tracker.

Found
2023-07-10
Patched
2023-08-02
Details
project zero root cause analysis

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1204 User Execution exploitation
  • T1059.004 Unix Shell primary impact
  • T1005 Data from Local System secondary impact
  • T1041 Exfiltration Over C2 Channel secondary impact
  • T1053 Scheduled Task/Job secondary impact
  • T1105 Ingress Tool Transfer secondary impact
  • T1112 Modify Registry secondary impact
  • T1486 Data Encrypted for Impact secondary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
total
Assessed
3 y ago

Exploit prediction

99.81% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Metasploit exploit/windows/fileformat/winrar_cve_2023_38831 WinRAR CVE-2023-38831 Exploit metasploit exploit, excellent rank, 2023-08-23
  • group-ib.com https://www.group-ib.com/blog/cve-2023-38831-winrar-zero-day/ referenced PoC, tagged "exploit" by a source, unverified
  • bleepingcomputer.com https://www.bleepingcomputer.com/news/security/winrar-zero-day-exploited-since-april-to-hack-trading-accounts/ referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/174573/WinRAR-Remote-Code-Execution.html referenced PoC, tagged "exploit" by a source, unverified
  • blog.google https://blog.google/threat-analysis-group/government-backed-actors-exploiting-winrar-vulnerability/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • rarlab winrar

Classification

Weakness
  • CWE-351 Insufficient Type Distinction
  • CWE-345 Insufficient Verification of Data Authenticity

References

Sources

Fencer Vulns 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.