CVE-2026-41145
ADVISORY - githubSummary
Impact
What kind of vulnerability is it? Who is impacted?
An authentication bypass vulnerability in MinIO's STREAMING-UNSIGNED-PAYLOAD-TRAILER code path
allows any user who knows a valid access key to write arbitrary objects to any bucket without knowing
the secret key or providing a valid cryptographic signature.
Any MinIO deployment is impacted. The attack requires only a valid access key (the well-known default
minioadmin, or any key with WRITE permission on a bucket) and a target bucket name.
PutObjectHandler and PutObjectPartHandler call newUnsignedV4ChunkedReader with a signature
verification gate based solely on the presence of the Authorization header:
newUnsignedV4ChunkedReader(r, true, r.Header.Get(xhttp.Authorization) != "")
Meanwhile, isPutActionAllowed extracts credentials from either the Authorization header or the
X-Amz-Credential query parameter, and trusts whichever it finds. An attacker omits the
Authorization header and supplies credentials exclusively via the query string. The signature gate
evaluates to false, doesSignatureMatch is never called, and the request proceeds with the
permissions of the impersonated access key.
This affects PutObjectHandler (standard and tables/warehouse bucket paths) and
PutObjectPartHandler (multipart uploads).
Affected components: cmd/object-handlers.go (PutObjectHandler),
cmd/object-multipart-handlers.go (PutObjectPartHandler).
Affected Versions
All MinIO releases through the final release of the minio/minio open-source project.
The vulnerability was introduced in commit
76913a9fd
("Signed trailers for signature v4", PR #16484),
which added authTypeStreamingUnsignedTrailer support. The first affected release is
RELEASE.2023-05-18T00-05-36Z.
Patches
Fixed in: MinIO AIStor RELEASE.2026-04-11T03-20-12Z
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_20260411032012.0.0_amd64.deb |
| DEB | arm64 | minio_20260411032012.0.0_arm64.deb |
| RPM | amd64 | minio-20260411032012.0.0-1.x86_64.rpm |
| RPM | arm64 | minio-20260411032012.0.0-1.aarch64.rpm |
Container Images
# Standard
docker pull quay.io/minio/aistor/minio:RELEASE.2026-04-11T03-20-12Z
podman pull quay.io/minio/aistor/minio:RELEASE.2026-04-11T03-20-12Z
# FIPS
docker pull quay.io/minio/aistor/minio:RELEASE.2026-04-11T03-20-12Z.fips
podman pull quay.io/minio/aistor/minio:RELEASE.2026-04-11T03-20-12Z.fips
Homebrew (macOS)
brew install minio/aistor/minio
Workarounds
If upgrading is not immediately possible:
Block unsigned-trailer requests at the load balancer. Reject any request containing
X-Amz-Content-Sha256: STREAMING-UNSIGNED-PAYLOAD-TRAILERat the reverse proxy or WAF layer. Clients can useSTREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER(the signed variant) instead.Restrict WRITE permissions. Limit
s3:PutObjectgrants to trusted principals. While this reduces the attack surface, it does not eliminate the vulnerability since any user with WRITE permission can exploit it with only their access key.
Credits
- Finder: Arvin Shivram of Brutecat Security (@ddd)
Common Weakness Enumeration (CWE)
Improper Authentication
Improper Authentication
GitHub
3.9
CVSS SCORE
8.8high| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| github.com/minio/minio | golang | - | - | >=0.0.0-20230506025312-76913a9fd5c6,<=0.0.0-20260212201848-7aac2a2c5b7c | Not yet available |
CVSS:4 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges.
There is no loss of confidentiality within the Vulnerable System.
There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Vulnerable System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Vulnerable System.
There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
NIST
3.9
CVSS SCORE
8.8highGoLang
-
Bitnami
BIT-minio-2026-41145
-
CVSS SCORE
8.8highChainguard
CGA-m7c3-grrq-785x
-