CVE-2023-40477

Application crash via malformed recovery-volume filename

Published May 3, 2024 · Updated Nov 4, 2025

Buffer overflow in WinRAR before 6.23 allows remote attackers to crash the application by inducing a user to unpack crafted recovery files. The old RAR 3.0 recovery-volume path processes a malformed REV filename without adequate bounds validation, overwriting the buffer edge with C++ object pointers. Exploitation requires a RAR file and malformed REV file in the same folder plus user-initiated unpacking; RARLAB reports no demonstrated code execution.

CVSS severity7.8
High
EPSS probability11.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Buffer overflow in WinRAR before 6.23 allows remote attackers to crash the application by inducing a user to unpack crafted recovery files. The old RAR 3.0 recovery-volume path processes a malformed REV filename without adequate bounds validation, overwriting the buffer edge with C++ object pointers. Exploitation requires a RAR file and malformed REV file in the same folder plus user-initiated unpacking; RARLAB reports no demonstrated code execution.

The record

CVE
CVE-2023-40477
Published
May 3, 2024
Updated
Nov 4, 2025
Vendor
RARLAB
Product
WinRAR
Classifications
CWE-129, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 3, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.21

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

RARLAB · WinRARversion=6.21

Published CVSS scores

7.8Trend Micro Zero Day InitiativeCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-129Improper Validation of Array Index
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo