# CVE-2026-42542: TDengine integer underflow in uvConnMayGetUserInfo

Source: https://junglewise.ai/threats/cve-2026-42542-tdengine-integer-underflow-in-uvconnmaygetuserinfo  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-10. Updated: 2026-06-10  
License: CC BY 4.0 with a link back

CVE-2026-42542 · Severity: high · CVSS 7.5 · Published 2026-06-10

TDengine is an open-source database designed to handle large amounts of data from Internet of Things (IoT) devices. A security flaw allows an unauthenticated attacker to crash the database server by sending a single specially crafted network packet. This results in a total service outage, preventing the system from recording or querying data until it is manually restarted.

Technologies: [TAOS Data TDengine](https://junglewise.ai/threats/technologies/tdengine). Vendors: [TAOS Data](https://junglewise.ai/threats/vendors/taos-data).

## Quick answers

**Is CVE-2026-42542 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42542 being exploited in the wild.

**How severe is CVE-2026-42542?** High severity, with a CVSS score of 7.5, published 10 June 2026.

**Which products and versions are affected?** TAOS Data TDengine 3.4.0.0 - 3.4.1.5.

**Is there a fix for CVE-2026-42542?** A patch was published on 2026-04-30: Version 3.4.1.6 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-42542 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-42542?** Check whether you run TAOS Data TDengine at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An integer underflow vulnerability exists in the `uvConnMayGetUserInfo()` function within `source/libs/transport/src/transSvr.c`. The root cause is a mixed-type subtraction involving the client-supplied `len` field and internal offsets without proper bounds checking. When an attacker sends a crafted RPC packet where `len` is smaller than the expected overhead, the subtraction results in a massive value (integer wrap-around), causing `memcpy` to trigger a segmentation fault. This can be exploited remotely without authentication or prior session state. The issue is resolved in version 3.4.1.6 by adding explicit length validation.

## Affected products

- taosdata TDengine 3.4.0.0 - 3.4.1.5

## Timeline

- 2026-04-30: patched: Version 3.4.1.6 released
- 2026-06-04: advisory: GitHub Security Advisory published
- 2026-06-10: disclosed: CVE published to NVD

## References

- [https://github.com/taosdata/TDengine/releases/tag/ver-3.4.1.6](https://github.com/taosdata/TDengine/releases/tag/ver-3.4.1.6)
- [https://github.com/taosdata/TDengine/security/advisories/GHSA-vg95-j2hf-hvjx](https://github.com/taosdata/TDengine/security/advisories/GHSA-vg95-j2hf-hvjx)

## Related threats

- [TDengine improper privilege management in Cloud DB instances](https://junglewise.ai/threats/cve-2026-62355-tdengine-improper-privilege-management-in-cloud-db-instances)
- [taosdata TDengine code injection in User-Defined Functions](https://junglewise.ai/threats/cve-2026-62350-taosdata-tdengine-code-injection-in-user-defined-functions)
- [taosdata TDengine stack buffer overflow in trimString](https://junglewise.ai/threats/cve-2026-62349-taosdata-tdengine-stack-buffer-overflow-in-trimstring)