CVE-2025-34164Public exploitNetwork attack vector

Unauthenticated code execution via broadcast-buffer underallocation

Published Aug 29, 2025 · Updated May 14, 2026

Heap-based buffer overflow in NetSupport Manager before 14.12.0000 allows remote attackers to execute arbitrary code through the Windows Client. The unauthenticated BC_ADD_PORT handler multiplies unchecked slot-size and slot-count values in 32-bit arithmetic, underallocating a heap broadcast buffer before BC_TCP_DATA writes outside it. A reachable Client listening on TCP port 5405 is sufficient; exploitation can crash client32.exe, and a demonstrated chain executes code in the Client process.

CVSS severity9.3
Critical
EPSS probability0.66%
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

Heap-based buffer overflow in NetSupport Manager before 14.12.0000 allows remote attackers to execute arbitrary code through the Windows Client. The unauthenticated BC_ADD_PORT handler multiplies unchecked slot-size and slot-count values in 32-bit arithmetic, underallocating a heap broadcast buffer before BC_TCP_DATA writes outside it. A reachable Client listening on TCP port 5405 is sufficient; exploitation can crash client32.exe, and a demonstrated chain executes code in the Client process.

The record

CVE
CVE-2025-34164
Published
Aug 29, 2025
Updated
May 14, 2026
Vendor
NetSupport Ltd.
Product
NetSupport Manager
Classifications
CWE-122, CAPEC-100, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 29, 2025CVE publishedPublication date reported by the CVE source.
  2. May 14, 2026Record 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=14.0 <14.12.0000

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NetSupport Ltd. · NetSupport Managerversion=14.0 <14.12.0000

Published CVSS scores

9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
CAPEC-100Overflow Buffers
T1210Exploitation of Remote Services

Public exploit references

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