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GHSA-2pxw-r47w-4p8c

HighCVSS 8.8 / 10
Published Sep 5, 2023·Last modified Feb 4, 2026
Affected Components(0)

No affected components available

Description

Impact

An attacker can use crafted requests to bypass metadata bucket name checking and put an object into any bucket while processing PostPolicyBucket. To carry out this attack, the attacker requires credentials with arn:aws:s3:::* permission, as well as enabled Console API access.

Patches

commit 67f4ba154a27a1b06e48bfabda38355a010dfca5
Author: Aditya Manthramurthy <donatello@users.noreply.github.com>
Date:   Sun Mar 19 21:15:20 2023 -0700

    fix: post policy request security bypass (#16849)

Workarounds

Browser API access must be enabled turning off MINIO_BROWSER=off allows for this workaround.

References

The vulnerable code:

// minio/cmd/generic-handlers.go
func setRequestValidityHandler(h http.Handler) http.Handler {
  return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    // ...
    // For all other requests reject access to reserved buckets
    bucketName, _ := request2BucketObjectName(r)
    if isMinioReservedBucket(bucketName) || isMinioMetaBucket(bucketName) {
      if !guessIsRPCReq(r) && !guessIsBrowserReq(r) && !guessIsHealthCheckReq(r) && !guessIsMetricsReq(r) && !isAdminReq(r) && !isKMSReq(r) {
        if ok {
          tc.FuncName = "handler.ValidRequest"
          tc.ResponseRecorder.LogErrBody = true
        }
        writeErrorResponse(r.Context(), w, errorCodes.ToAPIErr(ErrAllAccessDisabled), r.URL)
        return
      }
    }
    // ...
Risk Scores
Base Score
8.8

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
8.8

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS
6.68%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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