Vulnerability · Published Feb 15, 2024 · Assigned by wolfSSL
CVE-2023-6937Improper (D)TLS key boundary enforcement
Medium 5.3
In plain English
A medium-severity improper input validation in wolfSSL from wolfSSL. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
wolfSSL prior to 5.6.6 did not check that messages in one (D)TLS record do not span key boundaries. As a result, it was possible to combine (D)TLS messages using different keys into one (D)TLS record. The most extreme edge case is that, in (D)TLS 1.3, it was possible that an unencrypted (D)TLS 1.3 record from the server containing first a ServerHello message and then the rest of the first server flight would be accepted by a wolfSSL client. In (D)TLS 1.3 the handshake is encrypted after the ServerHello but a wolfSSL client would accept an unencrypted flight from the server. This does not compromise key negotiation and authentication so it is assigned a low severity rating.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | wolfssl | 5.6.6-r0 | ALPINE-CVE-2023-6937 |
| Alpine:v3.21 | wolfssl | 5.6.6-r0 | ALPINE-CVE-2023-6937 |
| Alpine:v3.22 | wolfssl | 5.6.6-r0 | ALPINE-CVE-2023-6937 |
| Alpine:v3.23 | wolfssl | 5.6.6-r0 | ALPINE-CVE-2023-6937 |
| Alpine:v3.24 | wolfssl | 5.6.6-r0 | ALPINE-CVE-2023-6937 |
| Debian:12 | wolfssl | no fix listed | DEBIAN-CVE-2023-6937 |
| Debian:13 | wolfssl | 5.6.6-1.2 | DEBIAN-CVE-2023-6937 |
| Ubuntu:22.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2023-6937 |
Affected products (as reported)
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N