How to Fix CVE-2026-7423: FreeRTOS-Plus-TCP (Bundle Sibling)
By Sai Kiran Pandrala
Last verified: 2026-05-25
CVE-2026-7423 is a sibling vulnerability in the same vendor advisory as CVE-2026-7422. Applying the patched build named in the primary write-up closes this CVE as well.
| Severity | CVSS 6 - Medium |
|---|---|
| Actively exploited? | Not currently in CISA KEV |
| Affected | Same as the bundle - see CVE-2026-7422 |
| Fixed in | Same patched build as CVE-2026-7422 (4.2.6, 4.4.1) |
| Type (CWE) | CWE-191: CWE-191: Integer Underflow (Wrap or Wraparound) |
What's different about CVE-2026-7423?
Integer underflow in the ICMP and ICMPv6 echo reply handlers in FreeRTOS-Plus-TCP before V4.4.1 and V4.2.6 allows an adjacent network user to cause a denial of service (device crash) when outgoing ping support is enabled, because header sizes are subtracted from a packet length field without validating the field is large enough, resulting in a heap out-of-bounds read of up to approximately 65KB.
To mitigate this issue, users should upgrade to the fixed version when available.
The technical impact and remediation are identical to the primary CVE in the bundle. The same vendor patch closes both.
How to fix CVE-2026-7423
Apply the patched build per the primary write-up: How to Fix CVE-2026-7422.
The patch installation procedure, verification commands, and interim mitigations are documented there. Reusing one runbook keeps the rollout consistent across the bundle.
Frequently asked questions
Is CVE-2026-7423 fixed by the same patch as CVE-2026-7422?
Yes. CVE-2026-7423 ships in the same vendor advisory as CVE-2026-7422. Applying the patched build named in the primary write-up closes both.
What is the CVSS score for CVE-2026-7423?
The CVSS base score is 6 (Medium).
Is it being exploited?
It is not currently listed in CISA KEV.
References
- Official vendor advisory: https://aws.amazon.com/security/security-bulletins/2026-021-aws/
- NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-7423
- CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- Primary write-up: How to Fix CVE-2026-7422
*Part of the FreeRTOS-Plus-TCP bundle. Full procedure at CVE-2026-7422.*