CVE-2021-39235Network attack vector

Unauthorized block writes via unchecked token access mode

Published Nov 19, 2021 · Updated Aug 4, 2024

Improper authorization in Apache Ozone before 1.2.0 allows remote authenticated users with a READ block token to write to the same block. The Datanode block-token verifier grants all operations without validating the token access-mode parameter against the requested operation. Exploitation requires authentication and a valid READ token, and successful use can overwrite data in the referenced block.

CVSS severity6.5
Medium
EPSS probability1.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in Apache Ozone before 1.2.0 allows remote authenticated users with a READ block token to write to the same block. The Datanode block-token verifier grants all operations without validating the token access-mode parameter against the requested operation. Exploitation requires authentication and a valid READ token, and successful use can overwrite data in the referenced block.

The record

CVE
CVE-2021-39235
Published
Nov 19, 2021
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Ozone
Classifications
CWE-732, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0 <=1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Apache Software Foundation · Apache Ozoneversion=1.0 <=1.0

Published CVSS scores

4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-732Incorrect Permission Assignment for Critical Resource
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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