CVE-2021-21390

mediumpriority · track · 24EPSS 0.009 · 58 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.85% (58th) EPSS

CVSS 4.3 · medium

Is it mine?

3 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · osv · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.04.3mediumAV:N/AC:M/Au:N/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 2.9

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 3.6

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:Nsecondary · ENISA EU

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:Nsecondary · security-advisories@github.comexploitability 2.8 · impact 3.6

v3.15.4mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-924USprimary

affected products (3)

Products and version ranges known to be affected.

minio minio≤ < RELEASE.2021-03-17T02-33-02Zenisa_euvdEU
minio minio< 2021-03-17t02-33-02znvdUScpe:2.3:a:minio:minio:*:*:*:*:*:*:*:*
Bitnami minio< 2021.03.17osvUSpkg:bitnami/minio

advisories (1)

Vendor and ecosystem advisories describing this.

BIT-minio-2021-21390MITM modification of request bodies in MinIO2024-03-06vendor · osvUS
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.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv nvd NVD CVE.org MITRE

published 2021-03-19modified 2026-06-17

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+40 more

references (10)

External citations — patches, advisories, analysis.

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