CVE Catalog

CVE-2026-103415

CriticalCVSS 9.3
Published: Translated: NVD NIST

Summary

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 contents of the cookie come from the peer, and the write occurs before certificate authentication completes, so a malicious or compromised server can overwrite memory past the TLS packet buffer without presenting a certificate. Only the client path is affected.

Risk Assessment

A malicious or compromised server can cause memory corruption on the client without a valid certificate, potentially leading to code execution or application crash.

Recommendation

Update the TLS library to a version containing the fix that validates the cookie size in HelloRetryRequest; if no fix is available, consider disabling TLS 1.3 on the client side.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS