CVE-2023-6937: medium-severity vulnerability in wolfSSL
Improper (D)TLS key boundary enforcement
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Affected products
wolfSSL · wolfSSLRelated CVEs — wolfSSL
In the same product, most dangerous first.
CVE-2017-13099HIGHwolfSSL Bleichenbacher/ROBOTEPSS 27.4%CVE-2017-2800HIGHCVE-2017-2800EPSS 8.5%CVE-2024-0901HIGHSEGV and out of bounds memory read from malicious packetEPSS 0.7%CVE-2023-3724CRITICALTLS 1.3 client issue handling malicious server when not including a KSE and PSK extensionEPSS 0.7%CVE-2023-6936MEDIUM Heap-buffer over-read with WOLFSSL_CALLBACKSEPSS 0.6%CVE-2026-5194CRITICALwolfSSL ECDSA Certificate VerificationEPSS 0.6%