CVE-2026-45321: TanStack Unspecified Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run TanStack TanStack. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-05-27, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-06-10; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns.
• EPSS 1.1%, percentile 64: FIRST’s model estimates a 1.1% chance of exploitation activity in the next 30 days, higher than 64% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
• Only applies if your dependency tree includes @tanstack/arktype-adapter (npm) = 1.166.12, fixed in 1.166.16; @tanstack/eslint-plugin-router (npm) = 1.161.9, fixed in 1.161.13; @tanstack/eslint-plugin-start (npm) = 0.0.4, fixed in 0.0.8; @tanstack/history (npm) = 1.161.9, fixed in 1.161.13. Check your lockfile, including transitive dependencies.
• Editorial verdict: Check exposure. Mini Shai-Hulud: TanStack npm Worm With Valid Provenance — If a lockfile picked up one of the bad TanStack Router/Start, Mistral or OpenSearch versions in mid-May 2026, treat that host as fully compromised and disable the dead-man's switch before rotating anything; everyone else can confirm and move on.

What it is

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 pullrequesttarget "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.

From the GitHub advisory

Summary

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 pullrequesttarget "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.

Impact

A user installing any affected version executes a payload (~2.3 MB obfuscated routerinit.js) at install time that:

CISA’s summary

TanStack contains an unspecified vulnerability that allowed malicious versions of the product to be published to the npm registry to publish credential-stealing malware under a trusted identity.

Weakness type: CWE-506.

Product: TanStack TanStack · Assigned by: GitHub_M · Published: 2026-05-12

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-05-27; federal due date 2026-06-10. Known ransomware use: Known.
• CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.05% probability of exploitation activity in the next 30 days; percentile 64.

Timeline

• 2026-05-11 — erroneo.us brief: Mini Shai-Hulud: TanStack npm Worm With Valid Provenance
• 2026-05-12 — CVE record published by GitHub_M
• 2026-05-12 — GitHub-reviewed advisory GHSA-g7cv-rxg3-hmpx published (critical)
• 2026-05-27 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-06-10 — CISA remediation deadline for US federal agencies
• 2026-08-04 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Listed in CISA KEV notes (github.com) github.com

Vulnerability records

1. GitHub Advisory GHSA-g7cv-rxg3-hmpx github.com
2. CVE.org record CVE-2026-45321 cve.org
3. NVD entry CVE-2026-45321 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

Other references from the CVE record and advisory

1. github.com github.com
2. tanstack.com tanstack.com
3. stepsecurity.io stepsecurity.io
4. socket.dev socket.dev

All exploited TanStack vulnerabilities · Critical npm advisories · Today’s Security Digest