CVE-2026-42809: Apache Polaris has an Improper Input Validation Issue

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• 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 0.6%, percentile 47: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 47% of all scored CVEs (low). 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-runtime-service (Maven) < 1.4.1, fixed in 1.4.1. Check your lockfile, including transitive dependencies.

What it is

Apache Polaris can issue broad temporary ("vended") storage credentials during staged table creation before the effective table location has been validated or durably reserved. Those temporary credentials are meant to limit the scope of accessible table data and metadata, but this scope limitation becomes attacker- directed because the attacker can choose a reachable target location. In the confirmed variant, if the caller supplies a custom location during stage create and requests credential vending, Apache Polaris uses that location to construct delegated storage credentials immediately. The stage-create path itself neither runs the normal location validation nor the overlap checks before those credentials are issued. Closely related to that, the staged-create flow also accepts write.data.path / write.metadata.path in the request properties and feeds those location overrides into the same effective table location set used for credential vending. Those fields are secondary to the main custom-location exploit, but they are still attacker-influenced location inputs that should be validated before any credentials are issued.

From the GitHub advisory

Apache Polaris can issue broad temporary ("vended") storage credentials during staged table creation before the effective table location has been validated or durably reserved. Those temporary credentials are meant to limit the scope of accessible table data and metadata, but this scope limitation becomes attacker-directed because the attacker can choose a reachable target location.

In the confirmed variant, if the caller supplies a custom location during stage create and requests credential vending, Apache Polaris uses that location to construct delegated storage credentials immediately. The stage-create path itself neither runs the normal location validation nor the overlap checks before those credentials are issued.

Closely related to that, the staged-create flow also accepts write.data.path / write.metadata.path in the request properties and feeds those location overrides into the same effective table location set used for credential vending. Those fields are secondary to the main custom-location exploit, but they are still attacker-influenced location inputs that should be validated before any credentials are issued.

Weakness type: CWE-862, CWE-20.

Product: org.apache.polaris:polaris-runtime-service (Maven) · Assigned by: apache · Published: 2026-05-04

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: low (any account)
• User interaction: none

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: 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): 0.58% probability of exploitation activity in the next 30 days; percentile 47.

Timeline

• 2026-05-04 — CVE record last updated
• 2026-05-04 — CVE record published by apache
• 2026-05-04 — GitHub-reviewed advisory GHSA-8ggj-j522-h5qf published (critical)

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. lists.apache.org lists.apache.org

Vulnerability records

1. GitHub Advisory GHSA-8ggj-j522-h5qf github.com
2. CVE.org record CVE-2026-42809 cve.org
3. NVD entry CVE-2026-42809 nvd.nist.gov

Other references from the CVE record and advisory

1. openwall.com openwall.com
2. github.com github.com
3. github.com github.com

Critical Maven advisories · Today’s Security Digest