How 37 pull requests pwned AsyncAPI's CI and backdoored npm packages

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On Monday July 14 2026, 37 pull requests landed in the asyncapi/generator repository. Most of them were noise: fake documentation tweaks, a charity-donation link, the kind of low-effort contribution a maintainer skims and forgets. One of them was not. That single PR exploited a misconfigured GitHub Actions workflow, walked out with a privileged access token, and used it to push directly to a release branch. At 07:10 UTC, four @asyncapi npm packages with roughly three million combined weekly downloads went out backdoored. The attacker never logged into npm. They never phoned a maintainer. They never touched a developer laptop. They just needed the CI pipeline to check out their code.

The push that stole the token happened at 06:58:42 UTC. The first malicious packages were live twelve minutes later. That gap is the whole story. Twelve minutes from a compromised token to backdoored packages, pulled by every CI job and every AI agent that ran an install in the exposure window. Then GitHub shipped the exact fix for this pattern 48 hours after the attack it would have prevented.

What AsyncAPI Is, and What a Pwn Request Is

AsyncAPI is the OpenAPI of event-driven systems: a specification and a toolchain for describing Kafka, MQTT and WebSocket APIs. The packages that got hit are the boring, load-bearing kind. @asyncapi/specs alone pulls about 2.66 million downloads a week. It rides in transitively through @asyncapi/parser (another 970K/week) on a semver range, so a lot of projects install it without ever naming it. When something this deep in the dependency graph ships a backdoor, the blast radius is measured in ecosystems, not in one repo's stargazers.

The root cause is a class of bug old enough to have a nickname. A "pwn request" is what you get when a workflow triggers on pull_request_target and then checks out the code from the pull request. Here is why that combination is poison. A normal pull_request workflow runs with a read-only token and no access to secrets, precisely because it executes untrusted fork code. pull_request_target is the opposite: it runs in the context of the base repository, with full read/write secrets, so maintainers can label PRs or post comments safely. Check out the fork's code inside that context and you have handed an outsider's script a token box full of your organization's secrets. This flaw is not new. It is the same shape that burned tj-actions/changed-files in 2025 and has been documented since 2020. AsyncAPI's own contributors knew. Someone opened a proof-of-concept PR on April 29. A fix splitting the workflow into isolated jobs was proposed on May 17 and sat unmerged for 58 days until the attacker used the exact hole it patched.

The Attack Flow

Here is the sequence, reconstructed from the StepSecurity and Wiz writeups.

The 37 PRs were cover. Reviewer attention is a finite resource, and a flood of trivial pull requests is a good way to spend it. Buried in that flood was the one PR whose payload targeted the vulnerable workflow. When CI ran it under pull_request_target, the attacker's code did one thing: scan the runner's environment for secrets and exfiltrate them to a dead-drop URL. The prize was the asyncapi-bot token, a service-account PAT with organization-wide write access.

With that token, the registry was irrelevant. At 06:58:42 UTC the attacker pushed commit 3eab3ec9 straight to the next branch of asyncapi/generator, signed with a giveaway placeholder identity: Your Name <[e-mail]>. Pushing to next is what a release is. The branch push tripped release-with-changesets.yml, AsyncAPI's own release automation, which dutifully built and published the packages to npm using AsyncAPI's own legitimate credentials. At 07:10 UTC, three packages went live: @asyncapi/generator@3.3.1, @asyncapi/generator-helpers@1.1.1, and @asyncapi/generator-components@0.7.1. Fifty minutes later the attacker repeated the trick against a second repo, spec-json-schemas, and shipped a poisoned @asyncapi/specs@6.11.2. The malicious versions stayed live between two and four hours before they were unpublished around 11:12 to 11:18 UTC.

Read that flow again and notice what is missing. No stolen npm account. No bypassed npm 2FA. No compromised maintainer machine. The npm registry was a passive recipient. It received a publish from AsyncAPI's real release pipeline, authenticated with AsyncAPI's real tokens, because from npm's point of view nothing was wrong. The compromise happened one layer up, in CI, and the registry just did its job.

Why Import-Time Execution Changes the Threat Model

Back in my write-up of the jscrambler compromise, the malware rode in on a preinstall hook. It fired the moment you typed npm install, before the package was even on disk. The defense that community reached for, correctly, was npm install --ignore-scripts, which tells npm not to run lifecycle scripts at all.

The AsyncAPI payload does not care about that defense. There is no preinstall, no postinstall, no install script anywhere in the package. The malware, a 3.08 MB bundled Node application that StepSecurity identified as Miasma RAT v3, is wired to execute when the module is require()d during normal use. Not at install time. At import time. It fires when your application boots and pulls the dependency into memory, which every application does, every single run.

That is the part worth internalizing. --ignore-scripts blocks the install-time door and does nothing about the import-time one. You can install a package with scripts fully disabled, audit the package.json, see no lifecycle hooks, and still get owned the first time your code does const specs = require('@asyncapi/specs'). Article-eight's advice was correct for article-eight's attack. This is the next layer down, and it needs a different answer.

CI/CD Is Now the Attack Surface

Put the two shifts together and you get the actual lesson. The entry point moved from the registry to your pipeline, and the trigger moved from install time to import time.

For an attacker, this is a strictly better deal. Stealing an npm publish token means defeating 2FA and hoping the maintainer does not notice a login. Compromising a CI workflow means finding one repository, out of the millions on GitHub, that mistriggers on pull_request_target and checks out fork code. Then the target's own release automation does the publishing, with the target's own credentials, and the packages look completely legitimate because they are legitimate, just carrying a passenger. There is no anomalous npm login to alert on. The malicious commit is signed Your Name <[e-mail]>, which nobody was watching for.

I run more than a dozen side projects on a Kanban board called KittyClaw, and several of them publish via GitHub Actions on branch push. Reading the AsyncAPI timeline, my honest reaction was not "those maintainers were careless." It was "which of my workflows checks out a PR I didn't write." That is the uncomfortable question this attack asks of everyone with a release pipeline. Not whether your npm password is strong. Whether your CI grants secrets to code you have not read.

What Actually Helps, and What the Fix Does Not Cover

Two days after the attack, on July 16, GitHub backported safer pull_request_target defaults from actions/checkout v7 to every supported major version. The change makes checkout refuse to silently grab fork code in the dangerous context. It is a real fix and you should take the bump.

It is also not a complete one, and it is worth being precise about the gap. The v7 backport addresses pull_request_target combined with a checkout of the PR ref. It does nothing for the other ways untrusted input reaches a privileged workflow. Those include issue_comment triggers that parse comment bodies, workflow_dispatch with attacker-influenced external inputs, and run blocks that call git or gh directly to fetch and act on PR content. Treating "we upgraded checkout" as "we are safe" is exactly the false sense of closure that lets the next tj-actions happen.

The hardening that actually moves the needle is boring and structural:

• Pin workflow permissions to the minimum. Set permissions: explicitly at the top of every workflow and default it to contents: read. A workflow that cannot write cannot publish, no matter what token leaks.
• Put environment protection rules on any release workflow. GitHub environments let you gate a job behind required reviewers and restrict which branches can deploy. A push to next should not be able to publish to npm without a human approving the environment.
• Require two-person review for any workflow that can reach npm. If merging one PR can ship a package, one compromised or careless reviewer is your whole security model.

None of that is novel. AsyncAPI had a proposed fix in hand on May 17 and the attack still worked, which tells you the hard part is never knowing the fix. It is merging it before someone opens 37 pull requests to make sure you are not looking.

Closing

If you run CI/CD through GitHub Actions, spend an hour this week on one check. Grep your workflows for pull_request_target, issue_comment, and any run: step that fetches PR content, and verify what secrets those jobs can see. I did it across the KittyClaw projects the day I read the disclosure. ekioo, the TypeScript consulting site I run on Azure, uses the same GitHub Actions release pattern AsyncAPI did and sat inside the same exposure window before the July 16 fix. Auditing it was not optional.

The harness I use to run all of this, agents, pipeline and all, is open source: github.com/Ekioo/KittyClaw — MIT, star it if it is useful.

One honest question to close on, because I do not think the community has a clean answer yet: once the payload runs at import time instead of install time, and the packages are published by the victim's own legitimate pipeline, what is the detection signal? What are you actually watching for? If you have solved that better than "audit every workflow by hand," I want to hear it.