CVE-2026-8838: Amazon Redshift Python Driver RCE Flaw

CVE-2026-8838 Overview

CVE-2026-8838 is a code injection vulnerability in the amazon-redshift-python-driver (also known as redshift_connector) affecting versions before 2.1.14. The driver calls Python's eval() on data received from the server inside the vector_in() function. A rogue Redshift server or a man-in-the-middle (MITM) attacker positioned between the client and a legitimate server can return crafted vector data that triggers arbitrary Python code execution on the client host. The flaw is tracked as CWE-94: Improper Control of Generation of Code. AWS published Security Bulletin 2026-033 and fixed the issue in release v2.1.14.

Critical Impact

Unauthenticated network attackers can achieve arbitrary code execution on any client running a vulnerable amazon-redshift-python-driver build that connects to an attacker-controlled or intercepted Redshift endpoint.

Affected Products

• amazon-redshift-python-driver (PyPI package redshift_connector) versions earlier than 2.1.14
• Python applications, ETL jobs, and analytics tools embedding the vulnerable driver
• CI/CD pipelines and notebooks that connect to Amazon Redshift using the affected driver

Discovery Timeline

• 2026-05-18 - CVE-2026-8838 published to NVD
• 2026-05-19 - Last updated in NVD database
• Release v2.1.14 - Fix published in the amazon-redshift-python-driver GitHub repository and GHSA-29h4-r29x-hchv

Technical Details for CVE-2026-8838

Vulnerability Analysis

The amazon-redshift-python-driver implements type handlers that convert wire-protocol values from the Redshift server into Python objects. The vector_in() handler parses incoming vector type payloads and passes the server-supplied string directly into Python's built-in eval(). Because eval() executes any valid Python expression, a server response containing function calls or attribute lookups runs inside the client process with the privileges of the calling application. The result is unauthenticated remote code execution on the client when it processes a single malicious result row.

Exploitation requires no client interaction beyond issuing a query that returns a vector column. Any code path that materializes the result, including cursor iteration and pandas integration via fetch_dataframe, triggers the unsafe eval() call.

Root Cause

The root cause is the use of eval() as a deserialization primitive for untrusted server input [CWE-94]. The driver treats wire data as trusted Python source code instead of parsing it with a structured, non-executing parser such as ast.literal_eval or a dedicated vector decoder. No allowlist, sandbox, or length restriction is applied to the input.

Attack Vector

Two realistic attack scenarios exist. First, a rogue server: an attacker who controls a Redshift-compatible endpoint, such as a developer pointed at a malicious staging host, returns a crafted vector value and executes code on the client. Second, a man-in-the-middle attacker who can intercept or downgrade the connection, for example through TLS stripping or DNS hijacking on untrusted networks, replaces legitimate vector payloads with a Python expression that invokes os.system, subprocess.Popen, or imports a loader for second-stage malware. The malicious payload is a Python expression rather than a binary, so signature-based network controls are ineffective.

No verified public proof-of-concept code is referenced in the advisory. See GHSA-29h4-r29x-hchv for the upstream technical description.

Detection Methods for CVE-2026-8838

Indicators of Compromise

• Python processes hosting redshift_connector spawning unexpected child processes such as sh, bash, cmd.exe, powershell.exe, or python -c
• Outbound network connections from Python interpreters to non-Redshift destinations shortly after a database query
• Redshift client connections to unfamiliar hostnames, IP addresses outside known AWS ranges, or endpoints reached over plaintext or downgraded TLS
• New files written under user home directories or temp paths by a Python process that normally only reads query results

Detection Strategies

• Inventory installed Python packages across endpoints, build agents, and notebooks and flag any redshift_connector or amazon-redshift-python-driver version below 2.1.14
• Correlate process-tree telemetry to identify Python interpreters that execute shell, scripting, or LOLBin children immediately after Redshift connection events
• Monitor for TLS connections from Python processes that fail certificate validation or negotiate connections without sslmode=verify-full

Monitoring Recommendations

• Enable EDR child-process and command-line logging on hosts that run analytics, ETL, or BI tooling using Python
• Log Redshift client connections at the network layer and alert on destinations outside approved Redshift cluster endpoints
• Track package installations in CI/CD systems and fail builds that pin redshift_connector<2.1.14

How to Mitigate CVE-2026-8838

Immediate Actions Required

• Upgrade redshift_connector to version 2.1.14 or later on every host, container image, Lambda layer, and notebook environment
• Enforce sslmode=verify-full on all Redshift connections so MITM attackers cannot substitute server responses
• Restrict outbound traffic from analytics and ETL hosts to known Redshift endpoints only
• Rotate credentials and review process and network logs on any host that connected to an untrusted Redshift endpoint while running a vulnerable driver

Patch Information

AWS released the fix in amazon-redshift-python-driver version 2.1.14, available on PyPI and from the GitHub release page. Details are documented in AWS Security Bulletin 2026-033 and GitHub Security Advisory GHSA-29h4-r29x-hchv. The patch replaces the unsafe eval() call in vector_in() with a safe parser for vector values.

Workarounds

• If immediate upgrade is not possible, avoid issuing queries that return vector columns from the affected driver
• Pin connections to trusted, authenticated Redshift endpoints and require TLS with full certificate verification
• Run Python applications that use the driver under least-privilege service accounts with restricted filesystem and network egress

# Upgrade the driver to the patched release
pip install --upgrade "redshift_connector>=2.1.14"

# Verify the installed version
python -c "import redshift_connector; print(redshift_connector.__version__)"

# Enforce strict TLS when connecting
# (example connection arguments)
# redshift_connector.connect(
#     host="my-cluster.xxxx.region.redshift.amazonaws.com",
#     database="prod",
#     user="analyst",
#     password="...",
#     sslmode="verify-full",
# )