CVE-2026-103415GHSA-5pv3-rhf5-gwgq
NetX Duo: When a TLS 1.3 client processes a HelloRetryRequest, it copies the server's cookie into its second ClientHello without checking that the cookie fits in the outgoing packet. Both the length and the con
Eclipse Foundation NetX Duo
CVSS
9.3CriticalExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.28%Chance of exploitation activity in the next 30 days, higher than 19% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
What fixes it
No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.
Description
When a TLS 1.3 client processes a HelloRetryRequest, it copies the server's cookie into its second ClientHello without checking that the cookie fits in the outgoing packet. Both the length and the contents of that cookie come from the peer, and the write happens before certificate authentication completes, so a malicious or compromised server can overwrite memory past the caller supplied TLS packet buffer without presenting a certificate.
Only the client path is affected.
Text from CVE List
Affected versions 2
- NetX Duoaffected: all versions through 6.5.1.202602CVE List
- NetX Duounaffected: 6.5.2.202603CVE List