In plain terms, Apache Polaris is supposed to issue short-lived GCS credentials that only work…
CVE-2026-42811 is a critical-severity improper input validation vulnerability in Apache Polaris from Apache, with a CVSS 3.1 base score of 9.9 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 1.4.1 as the first without the flaw, so updating Apache Polaris to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Apache Polaris to 1.4.1 or a later version.
- Update Polaris to 1.4.1 or a later version.
- Read the advisory on lists.apache.org for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apache | Apache Polaris | before 1.4.1 | 1.4.1 |
| Apache | Polaris | before 1.4.1 | 1.4.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (apache.org).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.4 | Critical | CNA (apache.org) |
| CVSS 3.1 | 9.9 | Critical | CNA (apache.org) |
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
How developers prevent this class of flaw
- Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
- Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
- Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- openwall.com/lists/oss-security/2026/05/02/12Mailing List, Third Party Advisory
Other vulnerabilities in Apache Polaris
- 8.1 High severity
- 9.9 Critical severity
- 9.9 Critical severity
- 9.9 Critical severity
Recent Improper Input Validation vulnerabilities
- 8.8 High severity
- 7.8 High severity
- 8.3 High severity
- 7.1 High severity
- 7.1 High severity
- 7.2 High severity
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