FreeRTOS-Plus-TCP: Integer Underflow (Wrap or Wraparound)
CVE-2026-7424 is a high-severity integer underflow (wrap or wraparound) vulnerability in FreeRTOS-Plus-TCP from AWS, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 4.2.6, 4.4.1 as the first without the flaw, so updating FreeRTOS-Plus-TCP to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.22% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update FreeRTOS-Plus-TCP to 4.2.6 or 4.4.1, whichever matches your release line, or a later version.
- Read the advisory on aws.amazon.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| AWS | FreeRTOS-Plus-TCP | 4.0.0 up to, but not including, 4.2.6; 4.3.0 up to, but not including, 4.4.1 | 4.2.6, 4.4.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.2 | High | CNA |
| CVSS 3.1 | 8.1 | High | CNA |
Official description
Integer underflow in the DHCPv6 sub-option parser in FreeRTOS-Plus-TCP before V4.4.1 and V4.2.6 allows an adjacent network actor to corrupt the device's IPv6 address assignment, DNS configuration, and lease times, and to cause a denial of service (permanent IP task freeze requiring hardware reset) by sending a single crafted DHCPv6 packet. The issue is present whenever DHCPv6 is enabled. To mitigate this issue, users should upgrade to version V4.2.6 or V4.4.1 or newer.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Underflow (Wrap or Wraparound)
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Other vulnerabilities in FreeRTOS-Plus-TCP
- 8.1 High severity
Recent Integer Underflow (Wrap or Wraparound) vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.8 High severity
- 7.8 High severity
- 8.2 High severity
Spotted an error? Tell us.