CVE-2026-40454: Apache IoTDB Buffer Overflow Vulnerability

CVE-2026-40454 Overview

CVE-2026-40454 is an out-of-bounds read vulnerability in the Apache IoTDB C++ client caused by improper input validation [CWE-20]. The flaw resides in the TsBlock deserializer, which fails to validate malformed server data before reading memory. An attacker controlling or impersonating an IoTDB server can send crafted responses that crash the C++ client process. The vulnerability affects Apache IoTDB C++ client versions from 1.3.5 before 1.3.8 and from 2.0.5 before 2.0.10. Apache recommends upgrading to version 2.0.10, which contains the fix.

Critical Impact
A malicious or compromised IoTDB server can crash any connected C++ client by returning malformed TsBlock data, resulting in denial of service for time-series data consumers.

Affected Products

Apache IoTDB C++ client versions 1.3.5 through 1.3.7
Apache IoTDB C++ client versions 2.0.5 through 2.0.9
Applications embedding the vulnerable client library for IoTDB connectivity

Discovery Timeline

2026-07-10 - CVE-2026-40454 published to NVD
2026-07-10 - Last updated in NVD database

Technical Details for CVE-2026-40454

Vulnerability Analysis

The vulnerability lives in the TsBlock deserialization routine of the Apache IoTDB C++ client. TsBlock is the binary wire format IoTDB uses to transfer time-series query results between server and client. The C++ deserializer reads length and offset fields from the server payload without adequately validating that those values fall within the buffer bounds. When malformed data arrives, the client dereferences memory beyond the allocated block, producing an out-of-bounds read that terminates the client process.

Exploitation requires no authentication on the client side because the flaw triggers during response parsing. Any attacker able to influence server responses can weaponize the bug. This includes rogue servers, compromised IoTDB instances, or network attackers positioned between client and server on unencrypted connections. The impact is limited to availability of the client process, with no reported memory disclosure or code execution primitive.

Root Cause

The root cause is improper input validation [CWE-20] in the TsBlock deserializer. The parser trusts length descriptors embedded in the server response and uses them to index into fixed-size buffers. Missing bounds checks allow attacker-controlled offsets to drive reads past valid memory regions.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker delivers a crafted TsBlock payload to the vulnerable C++ client through a malicious server endpoint or an intercepted network path. Deserialization of the malformed block crashes the client, disrupting downstream applications that depend on time-series queries.

No verified public exploit code is available at this time. See the Apache Thread Discussion and the Openwall OSS-Security Update for the coordinated disclosure details.

Detection Methods for CVE-2026-40454

Indicators of Compromise

Unexpected crashes or segmentation faults in applications using the Apache IoTDB C++ client
Core dumps referencing TsBlock deserialization functions in the IoTDB client library
Repeated client reconnection attempts to IoTDB endpoints following abrupt termination
IoTDB server responses of anomalous size or structure captured during query operations

Detection Strategies

Inventory all applications linked against libiotdb C++ client versions 1.3.5 to 1.3.7 or 2.0.5 to 2.0.9
Monitor process exit codes and crash telemetry for services that consume IoTDB query results
Deploy network monitoring on IoTDB client-server sessions to identify malformed TsBlock frames
Correlate application crash events with concurrent IoTDB session activity in centralized logs

Monitoring Recommendations

Aggregate host and application crash logs into a centralized platform for anomaly correlation
Alert on repeated crash-restart cycles of processes that maintain IoTDB client sessions
Track outbound connections from client hosts to unauthorized IoTDB server endpoints
Review server-side query patterns for clients that disconnect abnormally during result streaming

How to Mitigate CVE-2026-40454

Immediate Actions Required

Upgrade the Apache IoTDB C++ client to version 2.0.10 in all deployments
Rebuild and redeploy any application binaries statically linked against vulnerable client versions
Restrict client connections to trusted IoTDB server endpoints only
Enable TLS on IoTDB client-server communication to prevent response tampering in transit

Patch Information

Apache has released version 2.0.10 of the IoTDB C++ client, which fixes the out-of-bounds read in the TsBlock deserializer. Users on the 1.3.x branch must migrate to a fixed release, as the advisory specifies 2.0.10 as the remediation target. Consult the Apache Thread Discussion for upgrade guidance.

Workarounds

Limit IoTDB client connectivity to servers within trusted network segments using firewall rules
Enforce mutual TLS authentication between C++ clients and IoTDB servers to block impersonation
Deploy watchdog processes to restart critical services that crash due to malformed responses
Isolate applications using the vulnerable client in restart-tolerant containers until patched

bash

# Configuration example
# Verify installed Apache IoTDB C++ client version
ldd ./your_iotdb_app | grep iotdb
strings /usr/local/lib/libiotdb_session.so | grep -i version

# Upgrade via source build to fixed version 2.0.10
git clone --branch v2.0.10 https://github.com/apache/iotdb.git
cd iotdb/iotdb-client/client-cpp
mvn package -P with-cpp -DskipTests