CVE-2026-7424 - Integer Underflow in DHCPv6 Sub-Option Parser in FreeRTOS-Plus-TCP

unknownCVE-2026-7424

Bulletin ID: 2026-022-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 2026/04/29 12:20 PM PDT Description: FreeRTOS-Plus-TCP is an open-source, scalable TCP/IP stack for FreeRTOS. We identified CVE-2026-7424, where an integer underflow issue in the DHCPv6 sub-option parser could allow an adjacent network user to corrupt the device's IPv6 address assignment, DNS configuration, and lease times, and to cause a denial of service (IP task freeze requiring hardware reset). Impacted versions: FreeRTOS-Plus-TCP >=V4.0.0 AND <=V4.2.5, >=V4.3.0 AND <= V4.4.0 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.

CSIRTS triage

vendor: FreeRTOS product: FreeRTOS-Plus-TCP Denial of serviceOtheraffected: >=V4.0.0 AND <=V4.2.5, >=V4.3.0 AND <= V4.4.0

What: An integer underflow in the DHCPv6 sub-option parser could allow an adjacent network user to corrupt device configurations and cause a denial of service.
Who is affected: Devices using FreeRTOS-Plus-TCP versions in the specified range.
Urgency: Remediation is important as it can lead to device unavailability requiring a hardware reset.
Action: Update to a fixed version of FreeRTOS-Plus-TCP.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: AWS Security Bulletins (INTL · vendor-psirt · site)
Severity: unknown
Published: 2026-06-05
Exploitation: Not in CISA KEV at last sync

Original advisory: https://aws.amazon.com/security/security-bulletins/rss/2026-022-aws/

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-74240.22% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 13% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-7424	coverage & exploitation status	NVD · CVE.org

Recent advisories for - Integer Underflow

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highGHSA-q4h4-gmj2-qvw2: golang.org/x/crypto: Invoking byte arithmetic causes underflow and panicghsa · 2026-06-25
criticalCVE-2026-44631: Apache HTTP Server: Heap Underflow in `ap_regname` via Signed Char Overflowmsrc · 2026-06-09
criticalCVE-2026-52919: batman-adv: fix tp_meter counter underflow during shutdownmsrc · 2026-06-09