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.
Published: 2026-10-14
Score: 9.3 Critical
EPSS: n/a
KEV: No
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Remediation

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History

Wed, 14 Oct 2026 17:45:00 +0000

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'}

Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: eclipse

Published:

Updated: 2026-10-14T17:36:17.620Z

Reserved: 2026-09-30T14:46:51.792Z

Link: CVE-2026-103415

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-14T18:17:19.790

Modified: 2026-10-14T18:17:19.790

Link: CVE-2026-103415

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses