CVE-2026-103415

critical · 9.3

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.

9.3

CVSS

0.3%

EPSS (exploit prob.)

21st

EPSS percentile

2026-10-14

Published

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Weaknesses

CWE-787

References

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

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-103415