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NHS Goes To War Against Open Source

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The NHS is preparing to close nearly all of its Open Source repositories.

Throughout my time working for the UK Government - in GDS, NHSX, i.AI, and others - I championed Open Source. I spoke to dozens of departments about it, wrote guidance still in use today, and briefed Ministers on why it was so important.

That's why I'm beyond disappointed at recent moves from NHS England to backtrack on all the previous commitments they've made about the value of open source to the UK's health service.

It's rare that multiple people leak the same story to me, but that's what gives me confidence that lots of people within the NHS are aghast at this news.

A few days ago, I was sent this quote which was attributed to a senior technical person in NHS England.

We are obviously looking at things like Mythos, which is more sophisticated at finding vulnerabilities. In the next week or so, we will be changing our tack on coding the open and making our code public until we're on top of that risk.

Most of our repos, unless they're essential, will be removed for security reasons.

As I've written before, this is not the correct response to the purported threat by Mythos. Neither the AI Safety Institute nor the NCSC recommend this action. While there may be some increase in risk from AI security scanners, to shutter everything would be a gross overreaction.

Nevertheless, that's what the NHS is preparing to do.

On the 29th of April, guidance note SDLC-8 was sent out. Here's what it says:

All source code repositories must be private by default. Repositories may be internal where there is a legitimate need for visibility within the enterprise. Repositories must not be public unless there is an explicit and exceptional need, and public access has been formally approved by the Engineering Board. Purpose Public repositories materially increase the risk of unintended disclosure of source code, architectural decisions, configuration detail, and contextual information that may be exploited — particularly given rapid advancements in Al models capable of large-scale code ingestion, inference, and reasoning (e.g. developments such as the Mythos model). This red line establishes a default-closed posture for code while the organisation assesses the impact of these changes and ensures that any public publication of code is a deliberate, reviewed, and justified decision. • For P&P Public repositories we will switch to Private on Monday the 11th May 2026 • Teams that have a need for an exemption need to declare this to the Engineering mailbox by COP Wednesday 6th May 2026 • Teams can change to private at any time ahead of this • Central tracking of public repositories: NHSE public repositories.xlsx

The majority of code repos published by the NHS are not meaningfully affected by any advance in security scanning. They're mostly data sets, internal tools, guidance, research tools, front-end design and the like. There is nothing in them which could realistically lead to a security incident.

When I was working at NHSX during the pandemic, we were so confident of the safety and necessity of open source, we made sure the Covid Contact Tracing app was open sourced the minute it was available to the public. That was a nationally mandated app, installed on millions of phones, subject to intense scrutiny from hostile powers - and yet, despite publishing the code, architecture and documentation, the open source code caused zero security incidents.

Furthermore, this new guidance is in direct contradiction to the UK's Tech Code of Practice point 3 "Be open and use open source" which insists on code being open.

Similarly, the Service Standard says:

There are very few examples of code that must not be published in the open.

The main reason for code to be closed source is when it relates to policy that has not yet been announced. In this case, you must make the code open as soon as possible after the policy is published.

You may also need to keep some code closed for security reasons, for example code that protects against fraud. Follow the guidance on code you should keep closed and security considerations for open code.

There's also the DHSC policy "Data saves lives: reshaping health and social care with data":

Commitment 601 – completed May 2022

We will publish a digital playbook on how to open source your code for health and care organisations

And, here's NHS Digital's stance on open source in their Software Engineering Quality Framework:

The position of all three of these documents is that we should code in the open by default.

All of which is reflected in the NHS service standard:

Public services are built with public money. So unless there's a good reason not to, the code they're based should be made available for other people to reuse and build on.

All of which is to say - open source should be baked into the DNA of the NHS by now. There are thousands of NHS repositories on GitHub. The work undertaken to assess all of them and then close them will be massive. And for what?

Even if we ignore the impracticality of closing all the code - it is too late! All that code has already been slurped up. If Mythos really is the ultimate hacker, hiding the code now does nothing. It has likely already retained copies of the repositories.

And if it were both practical and effective to hide source code - that doesn't matter. These AI tools are just as effective against closed-source. They can analyse binaries and probe websites with ease.

There are tens of thousands of NHS website pages which refer to their GitHub repos - will they all need to be updated? What's the cost of that?

I've no idea what led to NHS England making this retrograde decision - so I've send a Freedom of Information request to find out.

I am convinced that closing all their excellent open source work is the wrong move for the NHS. I hope they see sense and reverse course.

Until then, I've helped make sure that every single NHS repository has been backed up and, because the software licence permits it, can be re-published if the original is closed.

In the meantime, you should email your MP and tell them that the NHS is wrong to shutter its world-leading open source repositories.

Don't let them take away your right to see the code which underpins our nation's healthcare.

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42 thoughts on “NHS Goes To War Against Open Source”

  4. @Edent Ugh. Where I work it’s even worse – very little has ever been open sourced, but at least it was easy to share code internally. Recently our internal Gitlab has been reconfigured to remove the ability to set repos to “public” (anyone on the network) or “protected” (anyone signed into Gitlab), and only allow “private” (specific people or groups). Not just “default closed”, but “only closed”.

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  9. If this goes through, it would demonstrate an immature understanding to a mounting vulnerability problem, so it gives me a concern on two fronts: 1) the NHS is expected to reduce it's budget globally by 2% for the next several years and proprietary vendors will slow that timeline 2) more worrying, is the fact that this is simply not how vulnerability protection works. The issue is not whether they can read the code on an open source repository, it is knowing what the lockdown method for the specific server and chip that it lives on and supporting jurisdictional requirements and software sandboxes where needed. 3) The third bullet point no one asked for: Mythros has the ability to look at vulnerabilities, trace them down to the binary, and then review that sequence from other stacks. If this was immunology, this would be interspecies contagion, and that's new to software and it's quick. Mad Cow Disease Mythros.

    Contagion and isolation protocols are beginning to emerge, but open source spreads as a social contagion, so harder to truly stop the downstream effects from spreading in this moment. NHS is a downstream effect. Removing Open Source doesn't stop the threat, it likely makes these services more vulnerable to stale updates to patches. This is one of those rare occasions where talking about the actual reality of the consequences of this to an MP is important.

    Reply

  11. @Edent great write-up. There's an additional point (made by Bruce Schneier writing on "vulnerability economics"): it's very plausible that in the arms race between AI offence and defence that open source will have the edge, because everyone can collaborate on the defence of such software

    https://www.schneier.com/blog/archives/2026/04/cybersecurity-in-the-age-of-instant-software.html

    Cybersecurity in the Age of Instant Software - Schneier on Security

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  12. Story broken by New Scientist today, but it’s been in the unofficial rumour mill all week for those working inside NHSE. Terence Eden has put out a good explanatory blog post There is an open letter if you feel you would like to sign and share it.

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  13. Saw this interesting blog post today about how the NHS is apparently preparing to shut down all Open Source repos in response to models like Mythos posing a security risk. Sad to see this response from the NHS. Interestingly, the Linux kernel vulnerability I posted the other day was partially identified by AI. I can see why there’s a kneejerk reaction to close repos, but think it demonstrates a misunderstanding of cyber-security to move ahead with the idea… The code’s already out there; the mod...

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  23. Теренс Иден, участвовавший в продвижения открытых стандартов и открытого ПО в госучреждениях Великобритании, сообщил , что Национальная служба здравоохранения страны (NHS) готовится закрыть почти все...

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  28. Seems to be a pattern of our day and age? Keeping an open public #archive available becomes an act of civil disobedience."I am convinced that closing all their excellent open source work is the wrong move for the NHS. I hope they see sense and reverse course.Until then, I've helped make sure that every single NHS repository has been backed up and, because the software licence permits it, can be re-published if the original is closed."#NHS #OpenSource #ArchivesUnderPressure

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Trackbacks, Pingbacks, and Boosts

  2. […] very useful to me. There is a lot of discussion about Mythos and security testing, including some panic actions by the NHS; in that regard, the Curl team’s experience with Mythos is interesting. Overall, industry […]

  6. The NHS is planning to move from an open source software development model to a closed one due to fear of Mythos. As far as unintended consequences go, this is a big one, it's terrible, but it's not entirely surprising. The PR around Mythos has been threatening that the sky is falling, the world is ending, and millions of vulnerabilities will be found in the coming months (or even weeks) - so, is it really surprising that some organisations are making knee-jerk reactions?

    Now is a time for level heads and proper analysis, not knee-jerk reactions. "Keep calm and carry on" for lack of a better meme.

    Given that the sky probably isn't about to fall in on us, if you're in the UK please sign the petition at https://keepthingsopen.com urging the NHS not walk back on their commitments to open source.

    I also recommend the blog post "NHS Goes To War Against Open Source" by @Edent on this subject: https://shkspr.mobi/blog/2026/05/nhs-goes-to-war-against-open-source/

    #OpenSource #AI

  10. Unsurprising to see that while more and more of Europe is embracing - nay, mandating! - open source, our government is proving once again that it cares so very very little about doing anything to help others.

    Luckily there are lots of people out there (including Terence) who are trying to plug the technical and moral holes politicians are so good at making.

  12. Anthropic's breathless press releases about its vuln-scanning bot have kinetic effects that reduce security for everyone.

    Anthropic is a bad actor in the space.

What links here from around this blog?

  1. Guidance. AI, open code and vulnerability risk in the public sector. Guidance for safely publishing source code in the open, and reducing the risk of AI-accelerated vulnerability discovery.GDS weighs in on the NHS's decision to retreat from Open Source

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