Vulnerability · Published Apr 29, 2026 · Assigned by AMZN
CVE-2026-7426Out-of-Bounds Write via Unsanitized Prefix Length in Router Advertisement Processing in FreeRTOS-Plus-TCP
High 8.1
In plain English
A high-severity out-of-bounds write in FreeRTOS-Plus-TCP from AWS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities).
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| AWS | FreeRTOS-Plus-TCP | 4.0.0 – before 4.2.64.3.0 – before 4.4.1 |
Weakness: CWE-787 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
References
- https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.4.1 patch
- https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/releases/tag/V4.2.6 patch
- https://aws.amazon.com/security/security-bulletins/2026-023-aws/ vendor-advisory
- https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/security/advisories/GHSA-97qg-4359-xm3x third-party-advisory