CVE-2026-39396Public exploitNetwork attack vector

Service interruption via unbounded OCI plugin extraction

Published Apr 21, 2026 · Updated Apr 21, 2026

Resource exhaustion in OpenBao before 2.5.3 allows remote attackers to fill server disks through a crafted OCI plugin image. ExtractPluginFromImage in the OCI plugin downloader streams decompressed tar data through io.Copy without validating the header size or limiting bytes written. Exploitation requires control of the configured OCI registry and automatic plugin download or a reload, and disk exhaustion interrupts OpenBao and co-located services.

CVSS severity3.1
Low
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in OpenBao before 2.5.3 allows remote attackers to fill server disks through a crafted OCI plugin image. ExtractPluginFromImage in the OCI plugin downloader streams decompressed tar data through io.Copy without validating the header size or limiting bytes written. Exploitation requires control of the configured OCI registry and automatic plugin download or a reload, and disk exhaustion interrupts OpenBao and co-located services.

The record

CVE
CVE-2026-39396
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
OpenBao
Product
OpenBao
Classifications
CWE-674, CWE-770, CWE-400, T1499.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 2.5.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenBao · OpenBaoversion=< 2.5.3

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
3.1GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
CWE-770Allocation of Resources Without Limits or Throttling
CWE-400Uncontrolled Resource Consumption
T1499.001OS Exhaustion Flood

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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