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MinIO vulnerable to Path Traversal via msgpack Body in `ReadMultiple` Storage-REST Endpoint

Moderate severity GitHub Reviewed Published Apr 25, 2026 in minio/minio • Updated Jun 8, 2026

Package

gomod github.com/minio/minio (Go)

Affected versions

>= 0.0.0-20220724015452, < 0.0.0-20260414213245

Patched versions

0.0.0-20260414213245

Description

Impact

What kind of vulnerability is it? Who is impacted?

A path traversal vulnerability in MinIO's ReadMultiple internode storage-REST
endpoint allows a caller holding the cluster root JWT to read files from
outside the configured drive roots, bounded only by the MinIO process UID.

Distributed-erasure (multi-node) MinIO deployments are impacted. Single-node
standalone deployments do not register the route and are not affected. The
attack requires an HS512 JWT signed with MINIO_ROOT_PASSWORD and carrying
accessKey = MINIO_ROOT_USER — the same secret every peer in the cluster
holds to authenticate internode traffic, so a compromised peer or any actor in
possession of the root credential can mint one.

The ReadMultiple handler (cmd/storage-rest-server.go) decodes a msgpack
ReadMultipleReq body containing Bucket, Prefix, and Files fields and
forwards them to xlStorage.ReadMultiple (cmd/xl-storage.go) without
validation:

volumeDir := pathJoin(s.drivePath, req.Bucket)          // traversal resolves here
for _, f := range req.Files {
    fullPath := pathJoin(volumeDir, req.Prefix, f)
    data, mt, err = s.readAllDataWithDMTime(ctx, req.Bucket, volumeDir, fullPath)
}

pathJoin calls path.Clean, which resolves .. components and produces an
absolute path anywhere on the filesystem — it is not a root jail. The global
setRequestValidityMiddleware rejects .. in r.URL.Path and r.Form but
does not inspect request bodies, so msgpack-encoded traversal bypasses it.
Sibling storage methods (StatInfoFile, ReadFileHandler, ReadVersion)
validate their volume argument through s.getVolDir(volume), which rejects
..; ReadMultiple skips this call.

The attacker sends POST /minio/storage/{drivePath}/v63/rmpl with a
msgpack-encoded body carrying ../ sequences in the Bucket field. The
server opens the resulting path via os.OpenFile with O_RDONLY|O_NOATIME
and returns its contents in the msgpack response stream.

Impact by deployment:

  • Bare-metal with User=minio in the systemd unit — the O_NOATIME
    ownership check bounds the read to files owned by the MinIO UID. Reachable
    secrets include TLS private keys, KMS/KES key material, systemd credentials,
    and data belonging to other tenants sharing the same UID on the host.
    Secrets leaked this way persist across cluster credential rotation.

  • Containerized running as UID 0 (the historical default for the official
    Docker image, docker-compose examples, and Helm charts without
    securityContext.runAsNonRoot) — the primitive escalates to arbitrary
    host-filesystem disclosure: /etc/shadow, /root/**, Kubernetes
    service-account tokens, cloud-init metadata caches.

Affected components: cmd/storage-rest-server.go (ReadMultiple handler),
cmd/xl-storage.go (xlStorage.ReadMultiple).

CWE: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory
— 'Path Traversal')

CVSS v4.0 Score: 6.9 (Medium)

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

Affected Versions

All MinIO releases from RELEASE.2022-07-24T01-54-52Z through the final
release of the minio/minio open-source project, RELEASE.2025-09-07T16-13-09Z.

The vulnerability was introduced in commit
f939d1c18
("Independent Multipart Uploads",
PR #15346), which added the
ReadMultiple storage-REST endpoint as part of the multipart upload
redesign. The first affected release is RELEASE.2022-07-24T01-54-52Z.

Patches

Fixed in: MinIO AIStor RELEASE.2026-04-14T21-32-45Z (recommended
upgrade target). The fix — which removed the ReadMultiple handler, the
corresponding storage-driver method, the msgpack datatypes, the REST-client
wrapper, and the route registration — first shipped in MinIO AIStor
RELEASE.2024-10-23T19-38-07Z. Every AIStor release from
RELEASE.2024-10-23T19-38-07Z onward is unaffected; users should upgrade to
RELEASE.2026-04-14T21-32-45Z or later to pick up the accumulated fixes and
improvements shipped since.

Binary Downloads

Platform Architecture Download
Linux amd64 minio
Linux arm64 minio
macOS arm64 minio
macOS amd64 minio
Windows amd64 minio.exe

FIPS Binaries

Platform Architecture Download
Linux amd64 minio.fips
Linux arm64 minio.fips

Package Downloads

Format Architecture Download
DEB amd64 minio_20260414213245.0.0_amd64.deb
DEB arm64 minio_20260414213245.0.0_arm64.deb
RPM amd64 minio-20260414213245.0.0-1.x86_64.rpm
RPM arm64 minio-20260414213245.0.0-1.aarch64.rpm

Container Images

# Standard
docker pull quay.io/minio/aistor/minio:RELEASE.2026-04-14T21-32-45Z
podman pull quay.io/minio/aistor/minio:RELEASE.2026-04-14T21-32-45Z

# FIPS
docker pull quay.io/minio/aistor/minio:RELEASE.2026-04-14T21-32-45Z.fips
podman pull quay.io/minio/aistor/minio:RELEASE.2026-04-14T21-32-45Z.fips

Homebrew (macOS)

brew install minio/aistor/minio

Workarounds

If upgrading is not immediately possible:

  • Rotate the root credential and restrict who holds it. The exploit
    requires a JWT signed with MINIO_ROOT_PASSWORD. Treat the root credential
    as the host-filesystem disclosure primitive that it is: rotate it after any
    suspected exposure, store it only in the secret manager that bootstraps the
    cluster, and do not hand it to applications or operators who only need
    object-level access.

  • Do not run the MinIO container as UID 0. Set
    securityContext.runAsNonRoot: true (and a non-zero runAsUser) in
    Kubernetes manifests, or add --user to docker run. This reduces the
    blast radius from arbitrary host-filesystem disclosure to MinIO-UID-owned
    files only.

  • Restrict the internode storage-REST port at the network layer. In
    distributed deployments, the storage-REST route is served on the same port
    as the S3 API by default. Where feasible, use --internode-port to expose
    internode traffic on a separate interface reachable only from other cluster
    peers, and block that interface from client networks.

Credits

  • Finders: Discovered by Claude, Anthropic's AI assistant, and triaged by
    Adrian Denkiewicz at Doyensec in collaboration with Anthropic
    Research    .

Resources

References

@harshavardhana harshavardhana published to minio/minio Apr 25, 2026
Published to the GitHub Advisory Database May 5, 2026
Reviewed May 5, 2026
Published by the National Vulnerability Database May 11, 2026
Last updated Jun 8, 2026

Severity

Moderate

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 None
Privileges Required High
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity None
Availability None
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:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(94th percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2026-42600

GHSA ID

GHSA-xh8f-g2qw-gcm7

Source code

Credits

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