NVD / CVE Program· CNA GitHub_M

CVE-2026-39388: OpenBao's Certificate Authentication Allows Token Renewal With Different Certificate

Noroxi assessment

Priority: Monitor (action score 8/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.10% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. Administrator privileges are required. Special conditions such as timing or configuration are required.
Fixed version: openbao (Alpine:v3.23) 2.5.4-r0; github.com/openbao/openbao (Go) 0.0.0-20260420160924-abe84e1af4c3; openbao (openSUSE:Tumbleweed) 2.5.3-1.1.

Low priority for now. Upgrade to openbao (Alpine:v3.23) 2.5.4-r0; github.com/openbao/openbao (Go) 0.0.0-20260420160924-abe84e1af4c3; openbao (openSUSE:Tumbleweed) 2.5.3-1.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

OpenBao is an open source identity-based secrets management system. Prior to version 2.5.3, OpenBao's Certificate authentication method, when a token renewal is requested and `disable_binding=true` is set, attempts to verify the current request's presented mTLS certificate matches the original. Token renewals for other authentication methods do not require any supplied login information. Due to incorrect matching, the certificate authentication method would allow renewal of tokens for which the attacker had a sibling certificate+key signed by the same CA, but which did not necessarily match the original role or the originally supplied certificate. This implies an attacker could still authenticate to OpenBao in a similar scope, however, token renewal implies that an attacker may be able to extend the lifetime of dynamic leases held by the original token. This attack requires knowledge of either the original token or its accessor. This vulnerability is original from HashiCorp Vault. This is addressed in v2.5.3. As a workaround, ensure privileged roles are tightly scoped to single certificates.

LowCVSS 2.0 · v4.0—No exploit Fix available

Weak crypto

Published: Apr 20, 2026
Updated: Jun 17, 2026
EPSS: 0.1% · 0th percentile
CWE: CWE-295

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 8 / 40 · 2.0 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 2.0; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
openbao	openbao	cpe:2.3:a:openbao:openbao

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This vulnerability is about certificate validation or weak cryptography. The free SSL checker tests your certificate, enabled TLS versions and weak ciphers.

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

openbao openbaobefore 2.5.3

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

openbao openbao
- < 2.5.3affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Alpine:v3.23	openbao	before 2.5.4-r0	2.5.4-r0
Go	github.com/openbao/openbao	before 0.0.0-20260420160924-abe84e1af4c3	0.0.0-20260420160924-abe84e1af4c3
openSUSE:Tumbleweed	openbao	before 2.5.3-1.1	2.5.3-1.1

Same product

openbao: all records

Other highest-scoring records for the same primary product.

CVE-2026-33758OpenBao has Reflected XSS in its OIDC authentication error message
37Monitor
CVE-2026-63132OpenBao's Recovery Mode Vulnerable To Token Leakage via Timing Attack
36Monitor
CVE-2025-54997OpenBao: Privileged Operator May Execute Code on the Underlying Host
36Monitor

Published before and after this one in the same product

← EarlierCVE-2025-64761Nov 25, 2025 · OpenBao Privileged Operator Identity Group Root Escalation
30Monitor
← EarlierCVE-2026-33757Mar 27, 2026 · OpenBao lacks user confirmation for OIDC direct callback mode
33Monitor
Later →CVE-2026-39396Apr 20, 2026 · OpenBao has Decompression Bomb via Unbounded Copy in OCI Plugin Extraction (DoS)
26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
alpine:openbao	2.5.4-r0 · Alpine:v3.23	Package registry (OSV)
Go:github.com/openbao/openbao	0.0.0-20260420160924-abe84e1af4c3	Package registry (OSV)
opensuse:openbao	2.5.3-1.1 · openSUSE:Tumbleweed	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
Administrator privileges are required.
Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: High
Privileges required: High
User interaction: P
Scope: X

Weakness class (CWE)

CWE-295 · Improper Certificate Validation

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

A certificate validation error is silently swallowed instead of terminating the connection. Often, code added for a test environment makes its way into production.

The bug in code

The whole CWE-295 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

kotlin

1override fun checkServerTrusted(chain: Array<X509Certificate>, type: String) {
2  // Left empty for the test environment
3}

Fixed

kotlin

1val client = OkHttpClient.Builder()
2  .certificatePinner(
3    CertificatePinner.Builder()
4      .add("api.sirius.example", "sha256/…")
5      .build()
6  ).build()

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log

Fix✗ → ✓Sep 28, 2026, 10:46 PM UTC

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References

github.com/openbao/openbao/security/advisories/GHSA-7ccv-rp6m-rffr

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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