How severe is CVE-2026-41145?

No CVSS score has been assigned to CVE-2026-41145 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-41145?

CVE-2026-41145 affects the following packages: github.com/minio/minio (Go). Ecosystems affected: Go.

How do I fix CVE-2026-41145?

No patched version of github.com/minio/minio has shipped for CVE-2026-41145 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect CVE-2026-41145 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/minio/minio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-41145 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-41145?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-41145 can be triaged on real exposure rather than presence alone.

Is CVE-2026-41145 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-41145 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-41145?

CVE-2026-41145 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 29th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-41145?

CVE-2026-41145 is classified as Improper Authentication (CWE-287). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-41145 published, and has it been updated?

CVE-2026-41145 was published on April 22, 2026 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-41145 — minio

Fix: minio/minio@76913a9

CVE-2026-41145 is a Improper Authentication vulnerability in github.com/minio/minio. No vendor fix is recorded yet; mitigation options are listed below.

MinIO has an Unauthenticated Object Write via Query-String Credential Signature Bypass in Unsigned-Trailer Uploads

Also known asBIT-minio-2026-41145GHSA-hv4r-mvr4-25vwGO-2026-5437

Published

Apr 22, 2026

Updated

Aug 12, 2026

Affected

1 pkg

Patched

See advisory

Exploits

None indexed

Exploitation data as of Sep 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41145.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected

🐹github.com/minio/minio

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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

Users of the open-source minio/minio project should upgrade to MinIO AIStor RELEASE.2026-04-11T03-20-12Z or later.

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-TRAILER at the reverse proxy or WAF layer. Clients can use STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER (the signed variant) instead.
Restrict WRITE permissions. Limit s3:PutObject grants 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)

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/minio/minio`	≥ 0.0.0-20230506025312-76913a9fd5c6	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/minio/minio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of github.com/minio/minio has shipped for CVE-2026-41145 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-41145 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-41145. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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

O3 Security · Impact-Aware SCA

Is CVE-2026-41145 in your dependencies?

O3 Security finds CVE-2026-41145 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works