GHSA-59w7-v8rr-pr4p BIT-openbao-2026-71543 CVE-2026-71543 GO-2026-6556
OpenBao's Templated Policies Allow Privilege Escalation via Wildcard Characters
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.42%
- Chance of exploitation in the next 30 days. Higher than 36.49% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-863 Incorrect Authorization
- Fix
0.0.0-20260710001938-2d4ebafec5c5- Upgrade github.com/openbao/openbao to this version or later
Description
Impact
ACL Policies
OpenBao supports "templated polices": Policies with placeholders that are replaced at evaluation time.
This allows you to write a single policy which e.g. grants user "alice" access to all entries in a key value engine prefixed with alice/ while granting "bob" access to bob/, "carol" access to carol/, etc.
If the data used in the template can be controlled by an attacker (e.g. your system allows the user to freely select their username) and "globbing" characters are considered valid ( e.g. * is a valid username) they will be able to escalate their privileges.
The problematic characters are *, + and /.
PKI Secrets Engine allowed_uri_sans_template and allowed_domains Polices
The PKI secrets engine allows you to limit the "common names" a user can requests a TLS certificate for. Similar to the ACL polices this allows you to restrict e.g. "alice" to alice.example.com, "bob" to bob.example.com, etc. via templates.
Again, if an attacker can control this data freely, they can trick the PKI engine into using e.g. the *.example.com glob effectively allowing them to issue certificates for any subdomain of example.com
The problematic character in this case is *.
SSH Secrets Engine allowed_users and allowed_domains Polices
The SSH secrets engine allows you to limit the "principal" a user can request as SSH certificate for. Similar to ACL and PKI, this allows templates.
The problematic character in this case is , as the template result is split at all commas and each entry will be allowed.
Am I affected?
You are affected, if a) you use a templated policy (ACL, PKI or SSH) and b) your users can modify data used by your template freely.
If you can guarantee that the data used in your templates will never contain the problematic characters, you are not affected. For example, if you use {{ identity.entity.id }} in your policy, you are not affected, because identity.entity.id is randomly generated by OpenBao.
Even with this vulnerability patched: Using user controllable data in your policies is probably not the best idea.
Patches
All three have been patched in OpenBao v2.6.0.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/openbao/openbao | < 0.0.0-20260710001938-2d4ebafec5c5 |
0.0.0-20260710001938-2d4ebafec5c5 |
| github.com/openbao/openbao | >= 0.1.0, <= 1.1.5 |
No fix yet |
| github.com/openbao/openbao | < 0.0.0-20260710001938-2d4ebafec5c5>= 0.1.0 |
0.0.0-20260710001938-2d4ebafec5c5 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/openbao/openbao Go → 0.0.0-20260710001938-2d4ebafec5c5
- go
go get github.com/openbao/openbao@v0.0.0-20260710001938-2d4ebafec5c5 && go mod tidy
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- Present
- Privileges required
- High
- User interaction
- None
- Confidentiality (vulnerable system)
- High
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- High
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
Weakness
CWE-863: Incorrect Authorization
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
How to prevent it
- Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
- System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.
References
Advisories
Packages
Other links
- github.com/openbao/openbao/security/advisories/GHSA-59w7-v8rr-pr4p
- github.com/openbao/openbao/pull/3401
- github.com/openbao/openbao/pull/3473
- github.com/openbao/openbao/commit/2d4ebafec5c524408b3d4ac1198df909cb7ac8c1
- github.com/openbao/openbao/commit/e516ce508e1481504cadbfbf62052364339093bc
- github.com/hashicorp/vault/blob/main/CHANGELOG.md
- github.com/openbao/openbao/releases/tag/v2.6.0
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-xp3c-3jw3-4vcr OpenBao Skips Stricter Deny Policy for LIST operations | Medium | Also affects github.com/openbao/openbao |
| GHSA-34fc-gh42-pj53 OpenBao's Recovery Mode Vulnerable To Token Leakage via Timing Attack | Critical | Also affects github.com/openbao/openbao |
| GHSA-444v-8vxr-p36h OpenBao Agent Writes Secrets to Stdout | Low | Also affects github.com/openbao/openbao |
| GHSA-8w8f-r2xv-4q4j OpenBao: Transit secrets engine crashes on key creation with `derived: true` for asymmetric key types | Medium | Also affects github.com/openbao/openbao |
| GHSA-mwr2-wmgp-crj6 OpenBao's System Backend allows Unauthorized Management of the containing Namespace | Low | Also affects github.com/openbao/openbao |
| GHSA-c36x-h252-g9x2 OpenBao: Cross-namespace lease revocation/renewal via canonical sys/leases/{revoke,renew} — incomplete fix of CVE-2026-45808 | Low | Also affects github.com/openbao/openbao |
| GHSA-6mwx-4547-5vc9 OpenBao: LDAPi ldaputil (wrong escape func) | Medium | Also affects github.com/openbao/openbao |
| GHSA-7j6w-vvw2-5f9c OpenBao's Kerberos Auth Method Accumulates Unaccessible Tokens | Medium | Also affects github.com/openbao/openbao |
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