CVE-2024-26256

Code execution via RAR E8 filter underflow

Published Apr 9, 2024 · Updated May 3, 2025

Heap-based buffer overflow in libarchive on affected Windows 11 and Windows Server builds allows attackers to execute code via a crafted RAR file. The execute_filter_e8 function accepts a four-byte filter length, then subtracts five in an unsigned loop bound, causing out-of-bounds memory access. A victim must process the crafted archive; successful exploitation runs code in the context of the processing application.

CVSS severity7.8
High
EPSS probability84.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in libarchive on affected Windows 11 and Windows Server builds allows attackers to execute code via a crafted RAR file. The execute_filter_e8 function accepts a four-byte filter length, then subtracts five in an unsigned loop bound, causing out-of-bounds memory access. A victim must process the crafted archive; successful exploitation runs code in the context of the processing application.

The record

CVE
CVE-2024-26256
Published
Apr 9, 2024
Updated
May 3, 2025
Vendor
Microsoft
Product
Windows Server 2022, 23H2 Edition (Server Core installation)
Classifications
CWE-122, CWE-787, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2024CVE publishedPublication date reported by the CVE source.
  2. May 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=10.0.25398.0 <10.0.25398.830

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Windows Server 2022, 23H2 Edition (Server Core installation)version=10.0.25398.0 <10.0.25398.830
Microsoft · Windows 11 Version 22H3version=10.0.22631.0 <10.0.22631.3447
Microsoft · Windows 11 Version 23H2version=10.0.22631.0 <10.0.22631.3447
Microsoft · Windows 11, version 22H2version=10.0.22621.0 <10.0.22621.3447

Published CVSS scores

7.8MicrosoftCVSS: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-122Heap-based Buffer Overflow
CWE-787Out-of-bounds Write
T1204.002Malicious 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

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Your stack

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