CVE-2021-21390

MITM modification of request bodies in MinIO

MEDIUM
5.9
CVSS Score
Published: March 19, 2021 at 04:00 PM UTC
Updated: June 17, 2026 at 03:35 AM UTC
1 product affected across 1 vendorMinIO

Using minio by minio?

Get instant alerts when new vulnerabilities affect minio - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM5.9
Exploit prediction
EPSS 0.9%

Description

MinIO is an open-source high performance object storage service and it is API compatible with Amazon S3 cloud storage service. In MinIO before version RELEASE.2021-03-17T02-33-02Z, there is a vulnerability which enables MITM modification of request bodies that are meant to have integrity guaranteed by chunk signatures. In a PUT request using aws-chunked encoding, MinIO ordinarily verifies signatures at the end of a chunk. This check can be skipped if the client sends a false chunk size that is much greater than the actual data sent: the server accepts and completes the request without ever reaching the end of the chunk + thereby without ever checking the chunk signature. This is fixed in version RELEASE.2021-03-17T02-33-02Z. As a workaround one can avoid using "aws-chunked" encoding-based chunk signature upload requests instead use TLS. MinIO SDKs automatically disable chunked encoding signature when the server endpoint is configured with TLS.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2021-03-17t02-33-02zv < RELEASE.2021-03-17T02-33-02Z
Affected range stops below 2021-03-17t02-33-02z, so it looks safe — our inference, not a vendor statement
Affected range stops below RELEASE.2021-03-17T02-33-02Z, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

x_refsource_MISCExploitPatchThird Party Advisory
https://github.com/minio/minio/pull/11801
x_refsource_CONFIRMExploitPatchThird Party Advisory
https://github.com/minio/minio/security/advisories/GHSA-xr7r-7gpj-5pgp

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-924

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card