KEVWire

Security intelligence, with context.

Response snapshot Oct 27, 2026, 06:19 UTC

Back to the wire
Permalink
VulnerabilityCVE-2026-42812

In Apache Iceberg, the table's metadata files are control files: they tell readers which data files belong to the table and which table version to read. `write.metadata.path`...

In Apache Iceberg, the table's metadata files are control files: they tell readers which data files belong to the table and which table version to read. `write.metadata.path` is an optional table property that tells Polaris where to write those metadata files.

At a glance

Exploited
Not known
Severity
9.4 Critical (CVSS 4.0)
Chance of exploitation
0.4% in the next 30 days
Sources
2 independent sources

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-42812 (opens a new tab)

What happened

In Apache Iceberg, the table's metadata files are control files: they tell readers which data files belong to the table and which table version to read.

`write.metadata.path` is an optional table property that tells Polaris where to write those metadata files. For a table already registered in a Polaris-managed catalog, changing only that property through an `ALTER TABLE`-style settings change (not a row-level `INSERT`, `SELECT`, `UPDATE`, or `DELETE`) bypasses the commit-time branch that is supposed to revalidate storage locations.

The full persisted / credential-vending variant requires the affected catalog to have `polaris.config.allow.unstructured.table.location=true`, with `allowedLocations` broad enough to include the attacker-chosen target.

`allowedLocations` is the admin-configured allowlist of storage paths that the catalog is allowed to use. Public project materials suggest that this flag is a real supported compatibility / layout mode, not just a contrived lab-only prerequisite.

Continue reading

In that configuration, a user who can change table settings can cause Apache Polaris itself to write new table metadata to an attacker-chosen reachable storage location before the intended location-validation branch runs.

If the later concrete-path validation also accepts that location, Polaris persists the resulting metadata path into stored table state. Later table-load and credential APIs can then return temporary cloud-storage credentials for the same location without revalidating it. In plain terms, Polaris can later hand out temporary storage access for the same attacker-chosen area.

That attacker-chosen area does not need to be limited to the poisoned table's own files. If it is a broader storage prefix, another table's prefix, or, depending on configuration or provider behavior, even a bucket/container root, the resulting disclosure or corruption scope can extend to any data and metadata Polaris can reach there.

The practical consequences are therefore similar to the staged-create credential-vending issue already discussed: data and metadata reachable in that storage scope can be exposed and, if write-capable credentials are later issued, modified, corrupted, or removed. Even before that later credential step, Polaris itself performs the metadata write to the unchecked location.

So the core issue is not only later credential vending.

The primary defect is that Polaris skips its intended location checks before performing a security- sensitive metadata write when only `write.metadata.path` changes.

When `polaris.config.allow.unstructured.table.location=false`, current code review suggests the later `updateTableLike(...)` validation usually rejects out-of-tree metadata locations before the unsafe path is persisted. That may reduce the persisted / credential-vending variant, but it does not prevent the underlying defect: Polaris still skips the intended pre-write location check when only `write.metadata.path` changes.

Scores and how they were measured

CVSS base severity

9.4

Version 4.0As of

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.4%

Scored Percentile 30.1%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-42812 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    Vendor advisory (via NVD references) (opens a new tab)

    The vendor advisory referenced by the CVE record, for affected versions and fixes.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  6. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-42812, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 26). In Apache Iceberg, the table's metadata files are control files: they tell readers which data files belong to the table and which table version to read. `write.metadata.path`... (CVE-2026-42812). https://kevwire.com/record/CVE-2026-42812

MLA

"In Apache Iceberg, the table's metadata files are control files: they tell readers which data files belong to the table and which table version to read. `write.metadata.path`... (CVE-2026-42812)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-42812.

Chicago

KEVWire. "In Apache Iceberg, the table's metadata files are control files: they tell readers which data files belong to the table and which table version to read. `write.metadata.path`... (CVE-2026-42812)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-42812.

Evidence summary (plain text)

In Apache Iceberg, the table's metadata files are control files: they tell readers
which data files belong to the table and which table version to read.



`write.metadata.path`... (May 4, 2026).
In Apache Iceberg, the table's metadata files are control files: they tell readers
which data files belong to the table and which table version to read.



`write.metadata.path` is an optional table property that tells Polaris
where to
write those metadata files. 
For a table already registered in a
Polaris-managed
catalog, changing only that property through an `ALTER TABLE`-style settings
change (not a row-level `INSERT`, `SELECT`, `UPDATE`, or `DELETE`) bypasses
the commit-time branch that is supposed to revalidate storage locations.

The full persisted / credential-vending variant requires the affected
catalog
to have `polaris.config.allow.unstructured.table.location=true`, with
`allowedLocations` broad enough to include the attacker-chosen target.


`allowedLocations` is the admin-configured allowlist of storage paths that
the
catalog is allowed to use. Public project materials suggest that this flag
is a
real supported compatibility / layout mode, not just a contrived lab-only
prerequisite.


In that configuration, a user who can change table settings can cause Apache Polaris
itself to write new table metadata to an attacker-chosen reachable storage
location before the intended location-validation branch runs.

If the later concrete-path validation also accepts that location, Polaris
persists the resulting metadata path into stored table state. Later
table-load
and credential APIs can then return temporary cloud-storage credentials for
the
same location without revalidating it. In plain terms, Polaris can later
hand
out temporary storage access for the same attacker-chosen area.

That attacker-chosen area does not need to be limited to the poisoned
table's
own files. If it is a broader storage prefix, another table's prefix, or,
depending on configuration or provider behavior, even a bucket/container
root,
the resulting disclosure or corruption scope can extend to any data and
metadata Polaris can reach there.



The practical consequences are therefore similar to the staged-create
credential-vending issue already discussed: data and metadata reachable in
that
storage scope can be exposed and, if write-capable credentials are later
issued, modified, corrup
CVSS 9.4 (version 4.0; evidence as of Oct 26, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-42812).
EPSS 0.4% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-42812&date=2026-10-26).
Sources:
NVD CVE-2026-42812: https://nvd.nist.gov/vuln/detail/CVE-2026-42812
Vendor advisory (via NVD references): https://lists.apache.org/thread/wxd2wj3p0smvrk84msv317wg5tp3jtw9
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T19:01:15.495Z&lastModEndDate=2026-10-26T20:30:55.133Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T18:27:03.991Z&lastModEndDate=2026-10-26T20:00:55.952Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T17:56:10.576Z&lastModEndDate=2026-10-26T19:25:57.867Z&resultsPerPage=500&startIndex=0
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-42812&date=2026-10-26
Record ID: CVE-2026-42812.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Analyzed. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

Your account

Email alerts

Email alerts are not available yet. To follow your stack today, use its RSS feed, which honors your filters, or connect an AI agent through the API.

Suggest an improvement

Ideas, missing sources, corrections, and bugs are all welcome. No account needed. Suggestions are reviewed by a person before anything changes.

Record details

Record detail