CVE-2026-39396: OpenBao: Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)
CVE-2026-39396 · Severity: low · CVSS 3.1 · Published 2026-04-21
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.
Yes. github.com/openbao/openbao (Go): upgrade to 0.0.0-20260420180337-2b2a901aa9f7 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-39396?
Check whether you run github.com/openbao/openbao (Go) or OpenBao at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
github.com/openbao/openbao (Go): upgrade to 0.0.0-20260420180337-2b2a901aa9f7 or later
go get github.com/openbao/openbao@v0.0.0-20260420180337-2b2a901aa9f7