CVE-2026-103415

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.

CVSS 4.0

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

EPSS

0.3% chance of exploitation in the next 30 days; higher than 20% of CVEs (scores of 2026-10-25)

CWE

CWE-787

Published

2026-10-14

Modified

2026-10-16

Record from

the NVD, synced 2026-10-19

References

• https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-5pv3-rhf5-gwgq
• https://gitlab.eclipse.org/security/cve-assignment/-/work_items/357

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