CVE-2026-39414
ADVISORY - githubSummary
Impact
What kind of vulnerability is it? Who is impacted?
MinIO's S3 Select feature is vulnerable to memory exhaustion when processing CSV
files containing lines longer than available memory. The CSV reader's nextSplit()
function calls bufio.Reader.ReadBytes('\n') with no size limit, buffering the entire
input in memory until a newline is found. A CSV file with no newline characters
causes the entire contents to be read into a single allocation, leading to an OOM
crash of the MinIO server process.
This is exploitable by any authenticated user with s3:PutObject and s3:GetObject
permissions. The attack is especially practical when combined with compression:
a ~2 MB gzip-compressed CSV can decompress to gigabytes of data without
newlines, allowing a small upload to cause large memory consumption on
the server. However, compression is not required — a sufficiently large uncompressed
CSV with no newlines triggers the same issue.
Affected component: internal/s3select/csv/reader.go, function
nextSplit().
CWE: CWE-770 (Allocation of Resources Without Limits or Throttling)
Affected Versions
All MinIO releases are through the final release of the minio/minio open-source project.
The vulnerability was introduced in commit https://github.com/minio/minio/commit/7c14cdb60e53dbfdad2be644dfb180cab19fffa7, which added S3 Select support for CSV.
The CSV reader has used unbounded line reads since this commit (originally via
Go's stdlib encoding/csv.Reader, later via bufio.Reader.ReadBytes after a refactor
in PR #8200.
The first affected release is RELEASE.2018-08-18T03-49-57Z.
Patches
Fixed in: MinIO AIStor RELEASE.2025-12-20T04-58-37Z
The fix replaces the unbounded bufio.Reader.ReadBytes('\n') call with a
byte-at-a-time loop that caps line scanning at 128 KB (csvSplitSize). If no
newline is found within this limit, the reader returns an error instead of
continuing to buffer.
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_20251220045837.0.0_amd64.deb |
| DEB | arm64 | minio_20251220045837.0.0_arm64.deb |
| RPM | amd64 | minio-20251220045837.0.0-1.x86_64.rpm |
| RPM | arm64 | minio-20251220045837.0.0-1.aarch64.rpm |
Container Images
# Standard
docker pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z
podman pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z
# FIPS
docker pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z.fips
podman pull quay.io/minio/aistor/minio:RELEASE.2025-12-20T04-58-37Z.fips
Homebrew (macOS)
brew install minio/aistor/minio
Workarounds
If upgrading is not immediately possible:
Disable S3 Select access via IAM policy. Deny the
s3:GetObjectaction with a condition restrictings3:prefixon sensitive buckets, or more specifically, denySelectObjectContentrequests at a reverse proxy by blockingPOSTrequests with?select&select-type=2query parameters.Restrict PutObject permissions. Limit
s3:PutObjectgrants to trusted principals to reduce the attack surface. Note: this reduces risk but does not eliminate the vulnerability since any authorized user can exploit it.
References
- Introducing commit:
7c14cdb60(PR #6127) - MinIO AIStor
Common Weakness Enumeration (CWE)
Allocation of Resources Without Limits or Throttling
Allocation of Resources Without Limits or Throttling
GitHub
-
CVSS SCORE
7.1high| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| github.com/minio/minio | golang | - | - | >=0.0.0-20180815103019-7c14cdb60e53 | Not yet available |
CVSS:4 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges.
There is no loss of confidentiality within the Vulnerable System.
There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
There is no loss of integrity within the Vulnerable System.
There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
NIST
2.8
CVSS SCORE
7.1highGoLang
-
Bitnami
BIT-minio-2026-39414
-
CVSS SCORE
7.1highChainguard
CGA-c5v5-555c-g3gg
-