The state of these docs has evolved since this task was originally filed. I investigated the current state of each of the landing pages and docs they link to; the following improvements are already in place:

• https://www.mediawiki.org/wiki/Security now has a (lovely!) navigation template with thematically grouped links that include sections for each of the groupings suggested in the original task (and more):
  • General MediaWiki security info and links to Manual are included under "Educational and Training material"
  • For developers: Resources include links to guides, training, and more, including links to https://www.mediawiki.org/wiki/Security/Training_resources and https://www.mediawiki.org/wiki/Security_for_developers (which is marked as an official development guideline).
    • For the specific programming language guides, I find only one draft of a GoLang security guide, but it's just a link of references. To me, this indicates it's likely not worthwhile for us to write or maintain our own security guides for these programming languages: there are many well-written guides already existing elsewhere, and we shouldn't create more maintenance burden by trying to create content of our own.
    • If there are Wikimedia or MediaWiki specific security guidelines relevant for specific programming languages, and they are lacking documentation, new separate tasks should be filed for that, so the Security teams and relevant product owners can triage and prioritize as needed. I would expect to find this type of information in the language-specific pages of the Development Guidelines collection of docs, with cross-references from this Security landing page (rather than putting this content within the Security docs collection).
  • Policies, processes services: covered by SOPs and Services section

• https://www.mediawiki.org/wiki/Wikimedia_Security_Team is now obsolete due to team restructuring; this page and other docs now (rightly) point to https://www.mediawiki.org/wiki/Product_Safety_and_Integrity

• https://meta.wikimedia.org/wiki/Security and https://wikitech.wikimedia.org/wiki/Security are primarily functioning as navigational or disambiguation landing pages, with what I think is an appropriate amount of content to help readers get to the relevant content on the other, more content-heavy landing pages. I think these should be left as-is. As part of my work on T415106, I added the "Security" tag to more docs on Meta, and added a link to the category page to the landing page, with a recommendation that people use that category to browse the relevant pages. The realm of security policy and related pages on Meta is large and has fuzzy boundaries, so if there's a prioritized workstream with clear requirements to update this, the topic could be revisited in the future.