---
title: "CVE-2026-27478: Unity Catalog has a JWT Issuer Validation Bypass tht Allows Complete User Impersonation"
url: https://erroneo.us/security/cve/CVE-2026-27478/
description: "CVE-2026-27478 (io.unitycatalog:unitycatalog-server (Maven)): Unity Catalog is an open, multi-modal Catalog for data and AI. In 0.4.0 and earlier, a…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-11
date_modified: 2026-05-11
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-27478"
kev: false
cvss: 9.1
epss: 0.00239
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-27478: Unity Catalog has a JWT Issuer Validation Bypass tht Allows Complete User Impersonation

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.2% , percentile 14: FIRST’s model estimates a 0.2% chance of exploitation activity in the next 30 days, higher than 14% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes io.unitycatalog:unitycatalog-server (Maven) <= 0.4.0, fixed in 0.4.1 . Check your lockfile, including transitive dependencies.

## What it is

Unity Catalog is an open, multi-modal Catalog for data and AI. In 0.4.0 and earlier, a critical authentication bypass vulnerability exists in the Unity Catalog token exchange endpoint (/api/1.0/unity-control/auth/tokens). The endpoint extracts the issuer (iss) claim from incoming JWTs and uses it to dynamically fetch the JWKS endpoint for signature validation without validating that the issuer is a trusted identity provider.

## Affected packages

- Maven `io.unitycatalog:unitycatalog-server` <= 0.4.0 → fixed: 0.4.1

## Affected products (CVE record)

- unitycatalog unitycatalog: <= 0.4.0

## Severity

- GitHub_M CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.24% probability of exploitation activity in the next 30 days; percentile 14.

## Sources

- [GitHub Advisory GHSA-qqcj-rghw-829x](https://github.com/advisories/GHSA-qqcj-rghw-829x)
- [CVE.org record CVE-2026-27478](https://www.cve.org/CVERecord?id=CVE-2026-27478)
- [NVD entry CVE-2026-27478](https://nvd.nist.gov/vuln/detail/CVE-2026-27478)
- [github.com](https://github.com/unitycatalog/unitycatalog/security/advisories/GHSA-qqcj-rghw-829x)
- [github.com](https://github.com/unitycatalog/unitycatalog/releases/tag/v0.4.1)

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Source page: https://erroneo.us/security/cve/CVE-2026-27478/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt