Audit plugin and theme update hygiene across a multi-site portfolio

Portfolio update-status export across 22 client sites managed from a central
dashboard:

[- 6 sites running at least one plugin that hasn't been updated by its
developer in 2+ years and no longer appears in the plugin repository
- 4 sites still on PHP 7.4, which reached end of life some time ago
- 9 sites have plugins flagged 3 or more major versions behind current
- 3 of the above sites take payments directly through a WooCommerce checkout,
the rest are brochure or content sites
- 1 site is running a plugin with a publicly disclosed unauthenticated RCE in
the version currently installed]

Prioritize and plan this the way an agency handling real client risk would, not
by list length:
1. Rank the 22 sites by actual exposure, not by count of outdated items: the
   site with a known unauthenticated RCE goes first regardless of anything
   else, then payment-processing sites on EOL PHP or abandoned plugins, then
   everything else.
2. For abandoned plugins with no repository listing, treat "update it" as often
   not an option, and lay out the real choices: find an actively maintained
   replacement with equivalent functionality, fork and patch internally if the
   plugin is small enough, or remove the feature if it's low-value.
3. For the RCE site specifically, give the immediate step before any planned
   maintenance window: is there a WAF rule or the plugin's own emergency
   mitigation that closes the hole today, since waiting for a scheduled update
   cycle isn't acceptable with that severity.
4. Draft a short client-facing update for the sites that need action, explaining
   what's outdated, what the real risk is in plain language, and what happens
   next, without either alarming a low-risk brochure-site client or
   under-selling the urgency to a checkout-site client.
5. Propose an ongoing cadence so this doesn't pile up again: staging-tested
   update windows, and an alerting threshold (for example, anything unpatched
   for 30+ days on a payment-processing site) that triggers proactive outreach
   instead of waiting for the next quarterly audit.