CVE-2026-103415

Published Oct 14, 2026 CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Eclipse
Eclipse netx Duo
Vendors & Products Eclipse
Eclipse netx Duo
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title TLS 1.3 HelloRetryRequest Buffer Overflow in NetX Duo Client
Type Values Removed Values Added
Title TLS 1.3 HelloRetryRequest Buffer Overflow in NetX Duo Client
Type Values Removed Values Added
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.
Weaknesses CWE-787
References
Metrics cvssV4_0

{'score': 9.3, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
eclipse
Published
Updated
Oct 16, 2026, 8:12 PM
Reserved
Sep 30, 2026, 2:46 PM
Status
Awaiting Analysis
Published
Oct 14, 2026, 6:17 PM
Modified
Oct 16, 2026, 9:17 PM