# CVE-2026-7424: Amazon FreeRTOS-Plus-TCP integer underflow in DHCPv6 parser

Source: https://junglewise.ai/threats/cve-2026-7424-amazon-freertos-plus-tcp-integer-underflow-in-dhcpv6-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-29. Updated: 2026-05-15  
License: CC BY 4.0 with a link back

CVE-2026-7424 · Severity: high · CVSS 8.1 · Published 2026-04-29

FreeRTOS-Plus-TCP is a networking library used by embedded devices to connect to the internet and local networks. A flaw in how the library processes network configuration messages (DHCPv6) allows an attacker on the same local network to crash the device or corrupt its network settings. This could lead to a total loss of connectivity for the device, requiring a physical hardware reset to restore service.

Technologies: [Amazon AWS](https://junglewise.ai/threats/technologies/aws), [Amazon Freertos-Plus-Tcp](https://junglewise.ai/threats/technologies/amazon-freertos-plus-tcp), [Amazon Web Services FreeRTOS-Plus-TCP](https://junglewise.ai/threats/technologies/freertos-plus-tcp). Vendors: [Amazon](https://junglewise.ai/threats/vendors/amazon), [Amazon Web Services](https://junglewise.ai/threats/vendors/amazon-web-services).

## Quick answers

**Is CVE-2026-7424 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-7424 being exploited in the wild.

**How severe is CVE-2026-7424?** High severity, with a CVSS score of 8.1, published 29 April 2026.

**Which products and versions are affected?** Amazon Web Services FreeRTOS-Plus-TCP >=V4.0.0, <=V4.2.5; >=V4.3.0, <= V4.4.0.

**Is there a fix for CVE-2026-7424?** A patch was published on 2026-04-29: Fixed in versions V4.4.1 and V4.2.6 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-7424 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-7424?** Check whether you run Amazon AWS, Amazon Freertos-Plus-Tcp or Amazon Web Services FreeRTOS-Plus-TCP 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 within the DHCPv6 sub-option parsing logic of the FreeRTOS-Plus-TCP stack. An attacker located on the same local network (adjacent) can send specially crafted DHCPv6 packets to trigger the underflow. This results in the corruption of critical network parameters, including IPv6 address assignments, DNS configurations, and lease times. Furthermore, the exploit can cause the IP task to freeze, leading to a permanent denial of service that necessitates a hardware reset. The issue is resolved in versions V4.4.1 and V4.2.6; a workaround involves disabling DHCPv6 via the ipconfigUSE_DHCPv6 configuration flag.

## Affected products

- Amazon Web Services FreeRTOS-Plus-TCP >=V4.0.0, <=V4.2.5; >=V4.3.0, <= V4.4.0

## Timeline

- 2026-04-29: disclosed
- 2026-04-29: patched: Fixed in versions V4.4.1 and V4.2.6

## References

- [https://aws.amazon.com/security/security-bulletins/rss/2026-022-aws/](https://aws.amazon.com/security/security-bulletins/rss/2026-022-aws/)

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