CVE-2022-43501 — KASAGO TCP/IP stack provided by Zuken Elmic generates ISNs(Initial Sequence Numb

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

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
ZUKEN Elmic	Kasago IPv6/v4 Dual	prior to Ver6.0.1.34
ZUKEN Elmic	Kasago IPv4	prior to Ver6.0.1.34
ZUKEN Elmic	Kasago IPv4 Light	prior to Ver6.0.1.34
ZUKEN Elmic	Kasago mobile IPv6	prior to Ver6.0.1.34

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-02-10T00:00:00.000Z
• Last modified: 2025-03-24T18:11:03.974Z

09References

• www.elwsc.co.jp — https://www.elwsc.co.jp/news/6352
• jvn.jp — https://jvn.jp/en/vu/JVNVU99551468/