CVE-2022-43501: KASAGO TCP/IP stack provided by Zuken Elmic generates ISNs(Initial Sequence Number) for TCP connections from a

Q: How do I fix CVE-2022-43501?

kasago ipv4: upgrade to 6.0.1.34; kasago ipv4 light: upgrade to 6.0.1.34; kasago ipv6\/v4 dual: upgrade to 6.0.1.34. Exact commands for each OS are on this page.

Q: Is CVE-2022-43501 being exploited?

CVE-2022-43501 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2022-43501 affect?

CVE-2022-43501 affects kasago ipv4, kasago ipv4 light, kasago ipv6\/v4 dual. Severity is critical (CVSS 9.1). KASAGO TCP/IP stack provided by Zuken Elmic generates ISNs(Initial Sequence Number) for TCP connections from an insufficiently random source. An attacker may be able to determine the ISN of the current or future TCP connections and either h

Q: How urgent is CVE-2022-43501?

Priority 49/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.1REMOTEUPGRADEUPGRADEUPGRADE

CVE-2022-43501 is a critical-severity flaw (CVSS 9.1) affecting kasago ipv4, kasago ipv4 light, kasago ipv6\/v4 dual. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

KASAGO TCP/IP stack provided by Zuken Elmic generates ISNs(Initial Sequence Number) for TCP connections from an insufficiently random source. An attacker may be able to determine the ISN of the current or future TCP connections and either hijack existing ones or spoof future ones.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-330
Published	2023-02-10
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: elwsc

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-02-10 04:15 UTCPublished CVE record published
2026-06-17 05:06 UTCUpdated Record last modified

elwsc kasago ipv4 UPGRADE

Affected: < 6.0.1.34

Fixed in: 6.0.1.34

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy kasago-ipv4 || rpm -q kasago-ipv4 || kasago-ipv4 --version

2. UPGRADE to 6.0.1.34 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade kasago-ipv4

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade kasago-ipv4

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

elwsc kasago ipv4 light UPGRADE

Affected: < 6.0.1.34

Fixed in: 6.0.1.34

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy kasago-ipv4-light || rpm -q kasago-ipv4-light || kasago-ipv4-light --version

2. UPGRADE to 6.0.1.34 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade kasago-ipv4-light

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade kasago-ipv4-light

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

elwsc kasago ipv6\/v4 dual UPGRADE

Affected: < 6.0.1.34

Fixed in: 6.0.1.34

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy kasago-ipv6v4-dual || rpm -q kasago-ipv6v4-dual || kasago-ipv6v4-dual --version

2. UPGRADE to 6.0.1.34 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade kasago-ipv6v4-dual

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade kasago-ipv6v4-dual

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

elwsc kasago mobile ipv6 UPGRADE

Affected: < 6.0.1.34

Fixed in: 6.0.1.34

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy kasago-mobile-ipv6 || rpm -q kasago-mobile-ipv6 || kasago-mobile-ipv6 --version

2. UPGRADE to 6.0.1.34 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade kasago-mobile-ipv6

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade kasago-mobile-ipv6

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2022-43501?

kasago ipv4: upgrade to 6.0.1.34; kasago ipv4 light: upgrade to 6.0.1.34; kasago ipv6\/v4 dual: upgrade to 6.0.1.34. Exact commands for each OS are on this page.

Is CVE-2022-43501 being exploited?

CVE-2022-43501 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2022-43501 affect?

CVE-2022-43501 affects kasago ipv4, kasago ipv4 light, kasago ipv6\/v4 dual. Severity is critical (CVSS 9.1). KASAGO TCP/IP stack provided by Zuken Elmic generates ISNs(Initial Sequence Number) for TCP connections from an insufficiently random source. An attacker may be able to determine the ISN of the current or future TCP connections and either h

How urgent is CVE-2022-43501?

Priority 49/100. Critical severity; Remotely exploitable, no login, no user action

References

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