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OpenBao's System Backend allows Unauthorized Management of the containing Namespace

Low severity GitHub Reviewed Published Jun 19, 2026 in openbao/openbao • Updated Jun 19, 2026

Package

gomod github.com/openbao/openbao (Go)

Affected versions

< 0.0.0-20260617103935-d3c1cc64b1ae
>= 0.1.0, <= 2.5.4

Patched versions

0.0.0-20260617103935-d3c1cc64b1ae

Description

Summary

A user that is granted namespace management (/sys/namespaces) capabilities within a non-root namespace ("the victim namespace") can abuse special handling of the literal path "root" in namespace path canonicalization to manage the victim namespace itself.

Details

Several endpoints under /sys/namespaces/* accept a namespace path segment that is canonicalized and then appended to the path of the sys mount's containing namespace (set via path prefix or X-Vault-Namespace header) to determine the absolute path of the namespace to operate on.

Given the special namespace path "root" canonicalizes to en empty path (""), when passed as /sys/namespaces/root, the resulting absolute namespace path remains equal to the sys mount's containing namespace. Given ACLs are evaluated before namespace path canonicalization, this allows users with capabilities on /sys/namespaces/root within any given namespace to operate on the namespace itself instead.

Impact

Users that were granted the required capabilities can abuse this vulnerability to:

  • Look up
  • Delete
  • Lock
  • Patch custom metadata

against the namespace containing the system backend they can manage sys/namespaces/root in. The exact range of operations that can be performed depends on the specific capabilities granted on said path and any sub-paths such as /api-lock.

Notably, the root namespace is immutable and cannot be modified, deleted or locked, and is thus unaffected. Also note that users can only abuse this vulnerability to operate on the direct parent or "containing" namespace relative to their capabilities, not arbitrary namespaces.

Patch

This will be fixed in OpenBao v2.5.5.

PoC

Start a development server:

bao server -dev

Create a namespace:

bao namespace create victim

This will be the namespace we gain unauthorized management of.

Create a policy that allows management of namespaces, inside of the victim
namespace.

bao policy write -namespace=victim namespace-management - <<EOF
path "sys/namespaces/*" {
	capabilities = ["read", "update", "patch", "delete"]
}
EOF

Then create a token with above policy attached:

export BAO_TOKEN=$(bao token create -namespace=victim -policy=namespace-management -field=token)

Operate on the victim's namespace using the token, for example by outright deleting it:

bao namespace delete -namespace=victim root

References

@cipherboy cipherboy published to openbao/openbao Jun 19, 2026
Published to the GitHub Advisory Database Jun 19, 2026
Reviewed Jun 19, 2026
Last updated Jun 19, 2026

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality None
Integrity Low
Availability Low
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

EPSS score

Weaknesses

Improper Authorization

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

CVE ID

CVE-2026-55775

GHSA ID

GHSA-mwr2-wmgp-crj6

Source code

Credits

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