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A comment on MITM on HTTPS traffic in Kazakhstan. Parent comment

Re:MITM on HTTPS traffic in Kazakhstan by wiml on Thursday July 18, 2019 @05:16PM (#20473986)
> most software doesn't support [name constraints] (and silently ignores them rather than correctly failing closed)

Could you elaborate on this? Specific examples? CVEs? My experience has been that most software will either honor them, or honor the "critical" flag, which is correct (if disappointing) behavior. If you want it to fail closed, use the critical flag. If you want it to fail open, clear the critical flag.

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Re:MITM on HTTPS traffic in Kazakhstan by JoshTriplett on Thursday July 18, 2019 @05:51PM (#20474252)
The last time I investigated this this, several years ago, I found that several SSL libraries simply ignored the extension entirely, whether it had "critical" or not. Older OpenSSL did so, for instance.

Doing some additional research, it looks like the situation has improved significantly now, and name constraints might actually work as designed if you don't care about older systems.

That still doesn't address the ability for a browser/administrator to apply such name constraints to a CA that didn't ship as part of its certificate, though.

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