Reproducible Builds in November 2025

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Welcome to the report for November 2025 from the Reproducible Builds project!

These monthly reports outline what we’ve been up to over the past month, highlighting items of news from elsewhere in the increasingly-important area of software supply-chain security. As always, if you are interested in contributing to the Reproducible Builds project, please see the Contribute page on our website.

In this report:

  1. “10 years of Reproducible Build” at SeaGL
  2. Distribution work
  3. Tool development
  4. Website updates
  5. Miscellaneous news
  6. Software Supply Chain Security of Web3
  7. Upstream patches

‘10 years of Reproducible Builds’ at SeaGL 2025

On Friday 8th November, Chris Lamb gave a talk called 10 years of Reproducible Builds at SeaGL in Seattle, WA.

Founded in 2013, SeaGL is a free, grassroots technical summit dedicated to spreading awareness and knowledge about free source software, hardware and culture. Chris’ talk:

[…] introduces the concept of reproducible builds, its technical underpinnings and its potentially transformative impact on software security and transparency. It is aimed at developers, security professionals and policy-makers who are concerned with enhancing trust and accountability in our software. It also provides a history of the Reproducible Builds project, which is approximately ten years old. How are we getting on? What have we got left to do? Aren’t all the builds reproducible now?


Distribution work

In Debian this month, Jochen Sprickerhof created a merge request to replace the use of reprotest in Debian’s Salsa Continuous Integration (CI) pipeline with debrebuild. Joschen cites the advantages as being threefold: firstly, that “only one extra build needed”; it “uses the same sbuild and ccache tooling as the normal build”; and “works for any Debian release”. The merge request was merged by Emmanuel Arias and is now active.

kpcyrd posted to our mailing list announcing the initial release of repro-threshold, which implements an APT transport that “defines a threshold of at least X of my N trusted rebuilders need to confirm they reproduced the binary” before installing Debian packages. “Configuration can be done through a config file, or through a curses-like user interface.

Holger then merged two commits by Jochen Sprickerhof in order to address a fakeroot-related reproducibility issue in the debian-installer, and Jörg Jaspert deployed a patch by Ivo De Decker for a bug originally filed by Holger in February 2025 related to some Debian packages not being archived on snapshot.debian.org.

Elsewhere, Roland Clobus performed some analysis on the “live” Debian trixie images, which he determined were not reproducible. However, in a follow-up post, Roland happily reports that the issues have been handled. In addition, 145 reviews of Debian packages were added, 12 were updated and 15 were removed this month adding to our knowledge about identified issues.

Lastly, Jochen Sprickerhof filed a bug announcing their intention to “binary NMU” a very large number of the R programming language after a reproducibility-related toolchain bug was fixed.


Bernhard M. Wiedemann posted another openSUSE monthly update for their work there.


Julien Malka and Arnout Engelen launched the new hash collection server for NixOS. Aside from improved reporting to help focus reproducible builds efforts within NixOS, it collects build hashes as individually-signed attestations from independent builders, laying the groundwork for further tooling.


Tool development

diffoscope version 307 was uploaded to Debian unstable (as well as version 309). These changes included further attempts to automatically attempt to deploy to PyPI by liaising with the PyPI developers/maintainers (with this experimental feature). […][…][…]

In addition, reprotest versions 0.7.31 and 0.7.32 were uploaded to Debian unstable by Holger Levsen, who also made the following changes:

  • Do not vary the architecture personality if the kernel is not varied. (Thanks to Raúl Cumplido). […]
  • Drop the debian/watch file, as Lintian now flags this as error for ‘native’ Debian packages. […][…]
  • Bump Standards-Version to 4.7.2, with no changes needed. […]
  • Drop the Rules-Requires-Root header as it is no longer required.. […]

In addition, however, Vagrant Cascadian fixed a build failure by removing some extra whitespace from an older changelog entry. […]


Website updates

Once again, there were a number of improvements made to our website this month including:


Miscellaneous news


Software Supply Chain Security of Web3

Via our mailing list, Martin Monperrus let us know about their recently-published page on the Software Supply Chain Security of Web3. The abstract of their paper is as follows:

Web3 applications, built on blockchain technology, manage billions of dollars in digital assets through decentralized applications (dApps) and smart contracts. These systems rely on complex, software supply chains that introduce significant security vulnerabilities. This paper examines the software supply chain security challenges unique to the Web3 ecosystem, where traditional Web2 software supply chain problems intersect with the immutable and high-stakes nature of blockchain technology. We analyze the threat landscape and propose mitigation strategies to strengthen the security posture of Web3 systems.

Their paper lists reproducible builds as one of the mitigating strategies. A PDF of the full text is available to download.


Upstream patches

The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where appropriate. This month, we wrote a large number of such patches, including:



Finally, if you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:



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