CVE-2026-93304
Publication date 27 September 2026
Last updated 5 October 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| wolfssl | 26.04 LTS resolute |
Needs evaluation
|
| 24.04 LTS noble |
Needs evaluation
|
|
| 22.04 LTS jammy |
Needs evaluation
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
Severity score breakdown
CVSS version:
Base score
6.3 · Medium
Vector: 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
Base score
3.7 · Low
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N