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CVE-2026-45321

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in TanStack. For every flaw being used in attacks, see Exploited flaws.

CVE-2026-45321 is a security flaw in TanStack. Attackers are using a flaw in TanStack that its maker hasn't described in detail. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 27 May 2026, and says ransomware gangs have used it.[1]

TanStack is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. TanStack has published a fix or advice.

Description

CISA calls it an unspecified in TanStack TanStack. In its words: “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.”[1]

The CVE record adds: “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.”[2]

The underlying weakness is CWE-506, in MITRE’s list of common software weaknesses.

It scores 9.6 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by the organisation that published the CVE using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; TanStack’s advisory has them[3]. CISA names the product as TanStack TanStack.

Most families won’t have TanStack; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 27 May 2026, 15 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 10 Jun 2026 to fix it.[1] CISA says ransomware gangs have used it.

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 3%. That’s in the top 12% of the flaws it scores.[4]

CISA assesses it as not automatable: each attack takes some work.

CISA doesn’t say who was attacked, or how.

Fix

TanStack has published a fix or advice.[3] CISA’s 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.”[1]

  1. Check whether you use it.TanStack is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 10 Jun 2026 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 9.6.[2]
CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 3%.[4]

See also

Similar flaws

  • CVE-2026-8398, Daemon Tools Lite: tools lite embedded malicious code ·
  • CVE-2026-48027, Nx Console: console embedded malicious code ·
  • CVE-2026-33634, Aquasecurity Trivy: embedded malicious code ·
  • CVE-2025-54313, Prettier eslint-config-prettier: embedded malicious code ·
  • CVE-2025-59374, ASUS Live Update: embedded malicious code ·

Added the same day

  • CVE-2026-8398, Daemon Tools Lite: tools lite embedded malicious code ·
  • CVE-2026-48027, Nx Console: console embedded malicious code ·

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “TanStack Unspecified Vulnerability”. Known Exploited Vulnerabilities Catalog, added 27 May 2026.
  2. ^ National Institute of Standards and Technology. “CVE-2026-45321 Detail”. National Vulnerability Database, published 12 May 2026.
  3. ^ TanStack. Advisories and fixes: github.com.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.033, percentile 88.4, 31 Oct 2026.
  5. CVE Program. “CVE-2026-45321”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.