How severe is CVE-2025-27821?

CVE-2025-27821 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2025-27821 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-27821?

CVE-2025-27821 affects Apache Hadoop. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-27821?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-27821 have an EU (EUVD) identifier?

Yes. CVE-2025-27821 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-206351.

When was CVE-2025-27821 published?

CVE-2025-27821 was published on 2026-01-26 and last updated on 2026-06-17.

CVE-2025-27821

CVE-2025-27821 is a high-severity vulnerability in Apache Hadoop with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 7.3)
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-206351
Weakness: CWE-787
Affected product: Apache Hadoop
Published: 2026-01-26
Last modified: 2026-06-17

Description

Out-of-bounds Write vulnerability in Apache Hadoop HDFS native client. This issue affects Apache Hadoop: from 3.2.0 before 3.4.2. Users are recommended to upgrade to version 3.4.2, which fixes the issue.

Frequently asked questions

What is CVE-2025-27821?: Out-of-bounds Write vulnerability in Apache Hadoop HDFS native client. This issue affects Apache Hadoop: from 3.2.0 before 3.4.2. Users are recommended to upgrade to version 3.4.2, which fixes the issue.
How severe is CVE-2025-27821?: CVE-2025-27821 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2025-27821 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-27821?: CVE-2025-27821 affects Apache Hadoop. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-27821?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-27821 have an EU (EUVD) identifier?: Yes. CVE-2025-27821 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-206351.
When was CVE-2025-27821 published?: CVE-2025-27821 was published on 2026-01-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:hadoop:*:*:*:*:*:*:*:*

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