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CVE-2026-39396— OpenBao has Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)

Quick assessment

Affected
openbao openbao
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

OpenBao是OpenBao开源的一个敏感数据管理软件。 OpenBao 2.5.3之前版本存在安全漏洞，该漏洞源于OCI插件下载器中的ExtractPluginFromImage函数在流式解压tar数据时未限制写入字节数，可能导致攻击者通过特制镜像进行解压炸弹攻击，造成磁盘耗尽。

CVSS 3.1 · Low EPSS 0.33% · P24

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking
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I. Basic Information for CVE-2026-39396

Vulnerability Information
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Vulnerability Title
OpenBao has Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)
Source: CVE Program / CVE List V5
Vulnerability Description
OpenBao is an open source identity-based secrets management system. Prior to version 2.5.3, `ExtractPluginFromImage()` in OpenBao's OCI plugin downloader extracts a plugin binary from a container image by streaming decompressed tar data via `io.Copy` with no upper bound on the number of bytes written. An attacker who controls or compromises the OCI registry referenced in the victim's configuration can serve a crafted image containing a decompression bomb that decompresses to an arbitrarily large file. The SHA256 integrity check occurs after the full file is written to disk, meaning the hash mismatch is detected only after the damage (disk exhaustion) has already occurred. This allow the attacker to replace **legit plugin image** with no need to change its signature. Version 2.5.3 contains a patch.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
OpenBao 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
OpenBao是OpenBao开源的一个敏感数据管理软件。 OpenBao 2.5.3之前版本存在安全漏洞，该漏洞源于OCI插件下载器中的ExtractPluginFromImage函数在流式解压tar数据时未限制写入字节数，可能导致攻击者通过特制镜像进行解压炸弹攻击，造成磁盘耗尽。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
openbao openbao < 2.5.3 -

II. Public POCs for CVE-2026-39396

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III. Intelligence Information for CVE-2026-39396

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Vendor Advisories for CVE-2026-39396 (1)

Same Patch Batch · openbao · 2026-04-21 · 4 CVEs total

CVE-2026-39388 OpenBao's Certificate Authentication Allows Token Renewal With Different Certificate
CVE-2026-39946 OpenBao allows SQL Injection in PostgreSQL database secrets engine
CVE-2026-40264 OpenBao's Token Store Allows Cross-Namespace Renewal, Revocation

IV. Related Vulnerabilities

Same product: openbao
Same vendor: openbao
Same weakness: CWE-400

V. Comments for CVE-2026-39396

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