CVE-2026-45321

This is a “supply-chain” attack: instead of breaking into your systems directly, attackers slipped malicious code into certain software packages you may install. If you install those versions, the malicious code can try to grab secrets from the machine running your install/build—like cloud access keys, GitHub tokens, and SSH keys—then send them to the attacker. Think of it like receiving a “trusted envelope” from the real sender that secretly contains a device designed to copy your keys as soon as it’s opened.

This matters if you use or build with the listed @tanstack/* packages (for example in your app, tooling, or CI). It’s especially relevant if your install or build runs in an environment that has access to secrets (cloud credentials, GitHub tokens, SSH keys), because the malicious packages were designed to steal those secrets after installation.
Reachability note: exploitation does not require a login to the software itself, but it requires that you install affected package versions—so you’re at risk when those exact vulnerable versions are reachable in your dependency tree and executed during your build/install.

This is a RED issue because real-world exploitation has been confirmed and it was added to CISA’s Known Exploited Vulnerabilities list. The activity involved credential theft targeting cloud credentials, GitHub tokens, and SSH keys, which can quickly lead to account and environment takeover. CISA’s remediation deadline is 2026-06-10—act immediately to update and rotate exposed secrets.

Confirm exposure

• Identify which packages you have installed: check your package.json and lockfiles (e.g., package-lock.json / yarn.lock / pnpm-lock.yaml) for any of these packages: arktype-adapter, eslint-plugin-router, eslint-plugin-start, history, nitro-v2-vite-plugin, react-router, react-router-devtools, react-router-ssr-query, react-start, react-start-client.
• Compare your installed versions against TanStack’s security advisory for GHSA-g7cv-rxg3-hmpx (linked in the TanStack remediation notes). If your lockfile pins to affected versions, you are exposed.

Upgrade path

• Update each affected package to the fixed versions specified in the TanStack advisory GHSA-g7cv-rxg3-hmpx.
• Reinstall using your package manager so the lockfile is updated (this ensures the build uses the corrected package tarballs).
• Re-run your build/tests to confirm the dependency graph no longer includes the affected versions.

Credential containment (do this even if you’re not sure)

• Because the malware specifically targeted cloud credentials, GitHub tokens, and SSH keys, rotate credentials that may have been present during installation or CI builds:
  • Revoke/rotate GitHub tokens used by CI.
  • Rotate cloud access keys used by the build environment.
  • Rotate any SSH keys used by deployment or CI.

Temporary workaround if you can’t patch immediately

• If you cannot upgrade right away, avoid building/installing in environments that contain high-value secrets.
• Use a restricted build environment with no cloud/GitHub/SSH credentials for at least the build where you test dependency updates.

Timing guidance

• CISA’s KEV entry lists a remediation due date of 2026-06-10.

What to monitor

• CI/CD logs for unexpected network calls or script execution during npm install / yarn install / build steps.
• Your GitHub/GCP/AWS credential usage alerts (new token creation, unusual access patterns).
• npm registry activity indicators if you have internal tooling to detect dependency integrity anomalies.

References to use in your ticket

• TanStack router advisory GHSA-g7cv-rxg3-hmpx (from TanStack’s remediation links)
• TanStack blog postmortem referenced in the vendor remediation section

Severity and status

• This is treated as a supply-chain compromise with credential theft impact; CISA lists it in KEV as exploited in the wild.

Mechanism (how it was triggered)

• Attackers published malicious npm package versions under a legitimate publisher identity.
• The chain involved:
  • a GitHub Actions workflow misconfiguration (pull_request_target “Pwn Request” class),
  • cache poisoning across the fork-to-base trust boundary,
  • and runtime memory extraction of the GitHub Actions OIDC token from the runner process.
• The result was malware shipped in specific versions of multiple @tanstack/* packages, designed to exfiltrate secrets from the environment that installed/built them.

Affected scope

• The findings list these canonical affected products: arktype-adapter, eslint-plugin-router, eslint-plugin-start, history, nitro-v2-vite-plugin, react-router, react-router-devtools, react-router-ssr-query, react-start, react-start-client.

Exploit maturity

• No public exploit code is on record, but exploitation is confirmed by CISA KEV and associated ransomware campaign usage.

EPSS

• EPSS is a prediction and does not override KEV-confirmed exploitation; therefore it is not used to drive action decisions.