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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| wolfSSL | wolfSSL | unaffected |
|
No data.
No data.
No data.
Project Subscriptions
No data.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
| Link | Providers |
|---|---|
| https://github.com/wolfSSL/wolfssl/pull/11458 |
|
History
Sun, 27 Sep 2026 09:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | (D)TLS 1.2 client accepts early ChangeCipherSpec before ClientKeyExchange | |
| Weaknesses | CWE-696 | |
| References |
| |
| Metrics |
cvssV4_0
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: wolfSSL
Published:
Updated: 2026-09-27T09:05:37.132Z
Reserved: 2026-09-17T16:55:11.172Z
Link: CVE-2026-93304
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses