CVE-2026-45321

CVE-2026-45321 is a critical-severity vulnerability in Tanstack Tanstack/arktype-adapter with a CVSS 3.x base score of 9.6. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-05-27). The underlying weakness is classified as CWE-506.

Key facts

Description

On 2026-05-11, between approximately 19:20 and 19:26 UTC, 84 malicious versions across 42 @tanstack/* packages were published to the npm registry. The publishes were authenticated via the legitimate GitHub Actions OIDC trusted-publisher binding for TanStack/router, but the publish workflow itself was not modified. The attacker chained three known vulnerability classes — a pull_request_target "Pwn Request" misconfiguration, GitHub Actions cache poisoning across the fork↔base trust boundary, and runtime memory extraction of the OIDC token from the Actions runner process — to publish credential-stealing malware under a trusted identity. Each affected package received exactly two malicious versions, published a few minutes apart.

Frequently asked questions

What is CVE-2026-45321?
On 2026-05-11, between approximately 19:20 and 19:26 UTC, 84 malicious versions across 42 @tanstack/* packages were published to the npm registry. The publishes were authenticated via the legitimate GitHub Actions OIDC trusted-publisher binding for TanStack/router, but the publish workflow itself was not modified. The attacker chained three known vulnerability classes — a pull_request_target "Pwn Request" misconfiguration, GitHub Actions cache poisoning across the fork↔base trust boundary, and runtime memory extraction of the OIDC token from the Actions runner process — to publish credential-stealing malware under a trusted identity. Each affected package received exactly two malicious versions, published a few minutes apart.
How severe is CVE-2026-45321?
CVE-2026-45321 has a CVSS 3.x base score of 9.6, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-45321 being actively exploited?
Yes. CVE-2026-45321 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-05-27, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2026-45321?
CVE-2026-45321 primarily affects Tanstack Tanstack/arktype-adapter. In total, 343 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-45321?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2026-45321 have an EU (EUVD) identifier?
Yes. CVE-2026-45321 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29352. It is also flagged as exploited in the EUVD (since 2026-05-27).
When was CVE-2026-45321 published?
CVE-2026-45321 was published on 2026-05-12 and last updated on 2026-06-17.

References

Affected products (343)

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