---
title: "CVE-2026-42811: Apache Polaris has an Improper Input Validation issue"
url: https://erroneo.us/security/cve/CVE-2026-42811/
description: "CVE-2026-42811 (org.apache.polaris:polaris-core (Maven)): In plain terms, Apache Polaris is supposed to issue short-lived GCS credentials that only work for…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-04
date_modified: 2026-05-08
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-42811"
kev: false
cvss: 9.4
epss: 0.00723
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-42811: Apache Polaris has an Improper Input Validation issue

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (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 0.7% , percentile 53: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 53% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes org.apache.polaris:polaris-core (Maven) < 1.4.1, fixed in 1.4.1 . Check your lockfile, including transitive dependencies.

## What it is

In plain terms, Apache Polaris is supposed to issue short-lived GCS credentials that only work for one table's files, but a crafted namespace or table name can cause those credentials to work across the configured bucket instead. Apache Polaris builds Google Cloud Storage downscoped credentials by creating a Credential Access Boundary (CAB) with CEL conditions that are intended to restrict access to the requested table's storage path. The relevant CEL string is built from the bucket name and the table path. That table path is derived from namespace and table identifiers. In current code, that path appears to be inserted into the CEL expression without escaping. As a result, a namespace or table identifier containing a single quote and other URI-safe CEL fragments can break out of the intended quoted string and change the meaning of the CEL condition. In private testing against Polaris 1.4.0 on real Google Cloud Storage, it was confirmed that Polaris accepted a crafted identifier and returned delegated GCS credentials whose CEL path restriction had effectively collapsed. Those delegated credentials could then: - list another table's object prefix; - read another table's metadata control file (Iceberg metadata JSON); - create and delete an object under another table's object prefix; - and also list, read, create, and delete objects under an unrelated external prefix in the same bucket that was not part of any table path. That last point is important. The issue is not limited to "another table". In the confirmed setup, once Apache Polaris returned credentials for the crafted table, the path restriction inside the configured bucket was effectively gone. The practical effect is that temporary credentials for one crafted table can be broader than the table Polaris was asked to authorize, and can become effectively bucket-wide within the configured bucket. The current GCS testing used a Polaris principal with broad catalog privileges for setup. A separate least-privilege Polaris RBAC variant has not yet been tested on GCS. However, the storage-credential broadening behavior itself has been confirmed on GCS.

## Affected packages

- Maven `org.apache.polaris:polaris-core` < 1.4.1 → fixed: 1.4.1

## Affected products (CVE record)

- Apache Software Foundation Apache Polaris: < 1.4.1

## Severity

- apache CVSS 4.0: 9.4 `CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
- apache CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 4.0: 9.4 `CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.72% probability of exploitation activity in the next 30 days; percentile 53.

## Sources

- [lists.apache.org](https://lists.apache.org/thread/hovn5hmkj9wj7v9cd8sn67svg03klgvg)
- [GitHub Advisory GHSA-fc3h-c6h7-r83j](https://github.com/advisories/GHSA-fc3h-c6h7-r83j)
- [CVE.org record CVE-2026-42811](https://www.cve.org/CVERecord?id=CVE-2026-42811)
- [NVD entry CVE-2026-42811](https://nvd.nist.gov/vuln/detail/CVE-2026-42811)
- [openwall.com](http://www.openwall.com/lists/oss-security/2026/05/02/12)
- [github.com](https://github.com/apache/polaris/commit/f86ce44053e52f77331d212106a9ab6b83c5cace)

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Source page: https://erroneo.us/security/cve/CVE-2026-42811/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt