It was discussed here in Cloudflare blames PCRE for outage and a blog at cloudflare but they found out a couple years ago even "seasoned programmers" can shoot themselves in the foot as well.

The cake is a lie.
The cake is a lie.
The cake is a lie.

In reply to Re^3: Is it safe to use external strings for regexes? by Fletch
in thread Is it safe to use external strings for regexes? by stevieb

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