CVE-2023-6937: Improper (D)TLS key boundary enforcement
First published: Thu Feb 15 2024(Updated: )
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.
Credit: facts@wolfssl.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| wolfSSL | <5.6.6 |
Remedy
The fix for this issue is located in the following GitHub Pull Request: https://github.com/wolfSSL/wolfssl/pull/7029 https://github.com/wolfSSL/wolfssl/pull/7029 .
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Reference Links
Frequently Asked Questions
What is the severity of CVE-2023-6937?
CVE-2023-6937 is considered a high-severity vulnerability due to its implications for data integrity in (D)TLS communications.
How do I fix CVE-2023-6937?
To fix CVE-2023-6937, update your wolfSSL library to version 5.6.6 or later, which addresses this vulnerability.
What systems are affected by CVE-2023-6937?
CVE-2023-6937 affects wolfSSL versions prior to 5.6.6 across all supported systems using this library.
What are the risks associated with CVE-2023-6937?
The risks associated with CVE-2023-6937 include potential unauthorized access to sensitive information and data leakage due to improper handling of (D)TLS messages.
Does CVE-2023-6937 affect (D)TLS 1.3 implementations?
Yes, CVE-2023-6937 affects (D)TLS 1.3 implementations, allowing for the combination of messages using different keys within the same record.
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