In the 5.7.2 release, a new macro WOLFSSL_MAX_ALT_NAMES was introduced to limit the maximum number of allowed subject alternative names to a default value of 128 to prevent a possible denial of service attack. Unfortunately, after the release, some commonly used certificates were brought to our attention that have more than 128 subject alternative names. If you started using 5.7.2 and hit error -161 on certificate handling this may be your problem. This issue can be immediately mitigated by building with WOLFSSL_MAX_ALT_NAMES at a number larger, say 512 or 1024. The wolfSSL master branch already has an increased default of 1024 which should be sufficient for all real world certificates and will be included in the 5.7.3 release.
If you have questions about any of the above, please contact us at facts@wolfSSL.com or +1 425 245 8247.
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