CVE-2026-39396 Details
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.
A denial-of-service vulnerability has been identified in OpenBao versions through 2.5.2. The issue arises in the OCI plugin downloader's 'ExtractPluginFromImage()' function, which extracts plugin binaries from container images by streaming decompressed tar data without any limit on the amount of data written. This flaw allows an attacker to exploit a compromised OCI registry by delivering a crafted image that includes a decompression bomb, which unpacks into a disproportionately large file. The vulnerability causes disk exhaustion on the OpenBao server, as the SHA256 integrity check is performed only after the entire file has been written, allowing the hash mismatch to be detected only after the damage has been done. This exploitation can disrupt co-located services and, if the extraction process is interrupted, leave behind partial files that are not automatically cleaned up.
Users are advised to update to OpenBao version 2.5.3, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 21, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/openbao/openbao/security/advisories/GHSA-r65v-xgwc-g56j | CISA-ADP | ExploitVendor Advisory |
| https://github.com/openbao/openbao/security/advisories/GHSA-r65v-xgwc-g56j | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-400 | Uncontrolled Resource Consumption | [email protected] |
| CWE-674 | Uncontrolled Recursion | [email protected] |
| CWE-770 | Allocation of Resources Without Limits or Throttling | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| openbao openbao | < 2.5.3 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 1, 2026 | Initial Analysis | [email protected] |
| Apr 21, 2026 | CVE Modified | CISA-ADP |
| Apr 21, 2026 | New CVE Received | [email protected] |