CVE-2023-3724: TLS 1.3 client issue handling malicious server when not including a KSE and PSK extension
First published: Mon Jul 17 2023(Updated: )
If a TLS 1.3 client gets neither a PSK (pre shared key) extension nor a KSE (key share extension) when connecting to a malicious server, a default predictable buffer gets used for the IKM (Input Keying Material) value when generating the session master secret. Using a potentially known IKM value when generating the session master secret key compromises the key generated, allowing an eavesdropper to reconstruct it and potentially allowing access to or meddling with message contents in the session. This issue does not affect client validation of connected servers, nor expose private key information, but could result in an insecure TLS 1.3 session when not controlling both sides of the connection. wolfSSL recommends that TLS 1.3 client side users update the version of wolfSSL used.
Credit: facts@wolfssl.com facts@wolfssl.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| WolfSSL wolfssl | <5.6.2 |
Remedy
Fixed in the following GitHub pull request https://github.com/wolfSSL/wolfssl/pull/6412 https://github.com/wolfSSL/wolfssl/pull/6412
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Reference Links
Frequently Asked Questions
What is the vulnerability ID for this issue?
The vulnerability ID for this issue is CVE-2023-3724.
What is the severity of CVE-2023-3724?
The severity of CVE-2023-3724 is critical with a CVSS score of 8.8.
Which software versions are affected by CVE-2023-3724?
The versions up to and excluding Wolfssl version 5.6.2 are affected by CVE-2023-3724.
What is the impact of CVE-2023-3724?
If a TLS 1.3 client connects to a malicious server without a PSK extension or a KSE extension, a predictable buffer is used for the IKM value, potentially compromising the session master secret.
How can CVE-2023-3724 be fixed?
Update to a version of Wolfssl that is above 5.6.2 to mitigate the vulnerability.
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