What’s Vulnerable › Vulnerabilities

CVE-2026-7426: Out-of-Bounds Write via Unsanitized Prefix Length in Router Advertisement Processing in FreeRTOS-Plus-TCP

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-29 · updated 2026-10-26
• Weakness: CWE-787

Description

Insufficient validation of the prefix length field in IPv6 Router Advertisement processing in FreeRTOS-Plus-TCP before V4.2.6 and V4.4.1 allows an adjacent network actor to cause memory corruption by sending a crafted Router Advertisement with a prefix length value exceeding the maximum valid length, resulting in a heap buffer overflow. Users processing IPv4 RA only are not impacted. To mitigate this issue, users should upgrade to the fixed version when available.

Affected products

• AWS FreeRTOS-Plus-TCP: from 4.0.0 before 4.2.6; from 4.3.0 before 4.4.1 — fixed in 4.2.6, 4.4.1

How to fix

Upgrade to a fixed version: AWS FreeRTOS-Plus-TCP 4.2.6, 4.4.1. Check the vendor advisory for mitigations.

References

• https://aws.amazon.com/security/security-bulletins/2026-023-aws/
• https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6
• https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1
• https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-97qg-4359-xm3x

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