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Fencer Intel
low 3.1

CVE-2026-39396 json

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

published 6mo ago modified last mo. also BIT-openbao-2026-39396 , EUVD-2026-24031 , GHSA-r65v-xgwc-g56j , GO-2026-5609

cvss
3.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/openbao/openbao 0.0.0-20260420180337-2b2a901aa9f7
  • bitnami openbao 2.5.3
  • openbao openbao 2.5.3
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • openbao openSUSE Tumbleweed 2.5.3-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2026:10594-1

  • openbao Alpine 3.24, Alpine 3.23 2.5.4-r0

alpine advisories ALPINE-CVE-2026-39396

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-39396 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-39396 updated cvss 5.9

OpenBao: OpenBao: Denial of Service via decompression bomb in OCI plugin extraction

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
6mo ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/openbao/openbao/security/advisories/GHSA-r65v-xgwc-g56j referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
GitHub 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
go github.com/openbao/openbao
<0.0.0-20260420180337-2b2a901aa9f7
0.0.0-20260420180337-2b2a901aa9f7
bitnami openbao
<2.5.3
2.5.3

Affected products

  • openbao openbao

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-674 Uncontrolled Recursion
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.