CVE-2026-39414: Github.com/minio/minio Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-h749-fxx7-pwpg",
  "modified" : "2026-07-21T14:48:16Z",
  "published" : "2026-04-09T17:32:31Z",
  "aliases" : [ "CVE-2026-39414" ],
  "summary" : "MinIO affected a DoS via Unbounded Memory Allocation in S3 Select CSV Parsing",
  "details" : "### Impact\n\n_What kind of vulnerability is it? Who is impacted?_\n\nMinIO's S3 Select feature is vulnerable to memory exhaustion when processing CSV \nfiles containing lines longer than available memory. The CSV reader's `nextSplit()` \nfunction calls `bufio.Reader.ReadBytes('\\n')` with no size limit, buffering the entire \ninput in memory until a newline is found. A CSV file with no newline characters \ncauses the entire contents to be read into a single allocation, leading to an OOM\ncrash of the MinIO server process.\n\nThis is exploitable by any authenticated user with `s3:PutObject` and `s3:GetObject` \npermissions. The attack is especially practical when combined with compression: \na ~2 MB gzip-compressed CSV can decompress to gigabytes of data without \nnewlines, allowing a small upload to cause large memory consumption on \nthe server. However, compression is not required — a sufficiently large uncompressed \nCSV with no newlines triggers the same issue.\n\n**Affected component:** `internal/s3select/csv/reader.go`, function\n`nextSplit()`.\n\n**CWE:** CWE-770 (Allocation of Resources Without Limits or Throttling)\n\n### Affected Versions\n\nAll MinIO releases are through the final release of the minio/minio open-source project.\n\nThe vulnerability was introduced in commit https://github.com/minio/minio/commit/7c14cdb60e53dbfdad2be644dfb180cab19fffa7, which added S3 Select support for CSV. \nThe CSV reader has used unbounded line reads since this commit (originally via \nGo's stdlib `encoding/csv.Reader`, later via `bufio.Reader.ReadBytes` after a refactor \nin [PR #8200](https://github.com/minio/minio/pull/8200). \n\nThe first affected release is `RELEASE.2018-08-18T03-49-57Z`.\n\n### Patches\n\n**Fixed in**: MinIO AIStor RELEASE.2025-12-20T04-58-37Z\n\nThe fix replaces the unbounded `bufio.Reader.ReadBytes('\\n')` call with a\nbyte-at-a-time loop that caps line scanning at 128 KB (`csvSplitSize`). If no\nnewline is found within this limit, the reader returns an error instead of\ncontinuing to buffer.\n\n#### Binary Downloads\n\n| Platform | Architecture | Download                                                                    |\n| -------- | ------------ | --------------------------------------------------------------------------- |\n| Linux    | amd64        | [minio](https://dl.min.io/aistor/minio/release/linux-amd64/minio)           |\n| Linux    | arm64        | [minio](https://dl.min.io/aistor/minio/release/linux-arm64/minio)           |\n| macOS    | arm64        | [minio](https://dl.min.io/aistor/minio/release/darwin-arm64/minio)          |\n| macOS    | amd64        | [minio](https://dl.min.io/aistor/minio/release/darwin-amd64/minio)          |\n| Windows  | amd64        | [minio.exe](https://dl.min.io/aistor/minio/release/windows-amd64/minio.exe) |\n\n#### FIPS Binaries\n\n| Platform | Architecture | Download                                                                    |\n| -------- | ------------ | --------------------------------------------------------------------------- |\n| Linux    | amd64        | [minio.fips](https://dl.min.io/aistor/minio/release/linux-amd64/minio.fips) |\n| Linux    | arm64        | [minio.fips](https://dl.min.io/aistor/minio/release/linux-arm64/minio.fips) |\n\n#### Package Downloads\n\n| Format | Architecture | Download                                                                                                                            |\n| ------ | ------------ | ----------------------------------------------------------------------------------------------------------------------------------- |\n| DEB    | amd64        | [minio_20251220045837.0.0_amd64.deb](https://dl.min.io/aistor/minio/release/linux-amd64/minio_20251220045837.0.0_amd64.deb)         |\n| DEB    | arm64        | [minio_20251220045837.0.0_arm64.deb](https://dl.min.io/aistor/minio/release/linux-arm64/minio_20251220045837.0.0_arm64.deb)         |\n| RPM    | amd64        | [minio-20251220045837.0.0-1.x86_64.rpm](https://dl.min.io/aistor/minio/release/linux-amd64/minio-20251220045837.0.0-1.x86_64.rpm)   |\n| RPM    | arm64        | [minio-20251220045837.0.0-1.aarch64.rpm](https://dl.min.io/aistor/minio/release/linux-arm64/minio-20251220045837.0.0-1.aarch64.rpm) |\n\n#### Container Images\n\n```bash\n# Standard\ndocker pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z\npodman pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z\n\n# FIPS\ndocker pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z.fips\npodman pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z.fips\n```\n\n#### Homebrew (macOS)\n\n```bash\nbrew install minio/aistor/minio\n```\n\n### Workarounds\n\n- [Users of the open-source `minio/minio` project should upgrade to MinIO AIStor `RELEASE.2025-12-20T04-58-37Z` or later.](https://docs.min.io/enterprise/aistor-object-store/upgrade-aistor-server/community-edition/)\n\nIf upgrading is not immediately possible:\n\n- **Disable S3 Select access via IAM policy.** Deny the `s3:GetObject` action\n  with a condition restricting `s3:prefix` on sensitive buckets, or more\n  specifically, deny `SelectObjectContent` requests at a reverse proxy by\n  blocking `POST` requests with `?select&select-type=2` query parameters.\n\n- **Restrict PutObject permissions.** Limit `s3:PutObject` grants to trusted\n  principals to reduce the attack surface. Note: this reduces risk but does not\n  eliminate the vulnerability since any authorized user can exploit it.\n\n### References\n\n- Introducing commit: [`7c14cdb60`](https://github.com/minio/minio/commit/7c14cdb60e53dbfdad2be644dfb180cab19fffa7) ([PR #6127](https://github.com/minio/minio/pull/6127))\n- [MinIO AIStor](https://min.io/aistor)",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/minio/minio"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.0.0-20180815103019-7c14cdb60e53"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/minio/minio/security/advisories/GHSA-h749-fxx7-pwpg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-39414"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/minio/minio/pull/8200"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/minio/minio/commit/7c14cdb60e53dbfdad2be644dfb180cab19fffa7"
  }, {
    "type" : "WEB",
    "url" : "https://docs.min.io/enterprise/aistor-object-store/upgrade-aistor-server/community-edition"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/minio/minio"
  }, {
    "type" : "WEB",
    "url" : "https://pkg.go.dev/vuln/GO-2026-5415?q"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-09T17:32:31Z",
    "nvd_published_at" : "2026-04-08T21:16:58Z"
  }
}