CVE-2026-93304 (GCVE-0-2026-93304)

Vulnerability from cvelistv5 – Published: 2026-09-27 09:05 – Updated: 2026-09-27 09:05
VLAI
Title
(D)TLS 1.2 client accepts early ChangeCipherSpec before ClientKeyExchange
Summary
A (D)TLS 1.2 client can accept a ChangeCipherSpec message before it has sent its ClientKeyExchange. No master secret has been derived at that point, so the client installs read keys derived from a known (deterministic) key and checks the server's Finished against that same key. An out-of-order ChangeCipherSpec can therefore be used by an attacker to complete the handshake in place of the server and send data the client accepts as authentic. The client's own traffic still uses correctly derived keys, so the attacker cannot read it, and the genuine server never completes the handshake. DTLS 1.2 clients are exposed because a datagram read can deliver the out-of-order records on its own. TLS 1.2 clients are exposed when the application supplies received bytes with wolfSSL_inject() or enables read ahead. For certificate suites, the attacker must be in a man-in-the-middle position. For PSK (Pre Shared Key) connections, any fake server can succeed without knowing the PSK.
Severity
6.3 (Medium)
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CWE
  • CWE-696 - Incorrect Behavior Order
Assigner
References
Impacted products
Vendor Product Version CPE status
wolfSSL wolfSSL Affected: 4.7.0 , ≤ 5.9.2 (semver)
guessed Create a notification for this product.
Date Public
2026-09-26 12:00
Credits
Anthropic OSS program
Show details on NVD website
To clipboard 

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