CVE-2022-43501Network attack vector

TCP session hijacking via weak ISN generation

Published Feb 10, 2023 · Updated Mar 24, 2025

Insufficiently random TCP ISNs in Zuken Elmic KASAGO before 6.0.1.34 allow remote attackers to hijack or spoof TCP sessions. For inbound connections, IPv4 and IPv6 TCP/IP processing ignores TM_USE_TCP_128BIT_RANDOM_ISS and uses KASAGO's proprietary random function instead of the RFC 6528 method. An unauthenticated network peer that derives present or future ISNs can inject traffic into an existing connection or impersonate an endpoint in a later one.

CVSS severity5.9
Medium
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficiently random TCP ISNs in Zuken Elmic KASAGO before 6.0.1.34 allow remote attackers to hijack or spoof TCP sessions. For inbound connections, IPv4 and IPv6 TCP/IP processing ignores TM_USE_TCP_128BIT_RANDOM_ISS and uses KASAGO's proprietary random function instead of the RFC 6528 method. An unauthenticated network peer that derives present or future ISNs can inject traffic into an existing connection or impersonate an endpoint in a later one.

The record

CVE
CVE-2022-43501
Published
Feb 10, 2023
Updated
Mar 24, 2025
Vendor
Zuken Elmic
Product
KASAGO Mobile IPv6
Classifications
CWE-330, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 24, 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=prior to Ver6.0.1.34

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zuken Elmic · KASAGO Mobile IPv6version=prior to Ver6.0.1.34
Zuken Elmic · KASAGO IPv6/v4 (Dual)version=prior to Ver6.0.1.34
Zuken Elmic · KASAGO IPv4 Lightversion=prior to Ver6.0.1.34
Zuken Elmic · KASAGO IPv4version=prior to Ver6.0.1.34

Published CVSS scores

5.9JPCERT/CCCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A: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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-330Use of Insufficiently Random Values
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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