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VulnerabilityPublished

CVE-2026-7423: AWS FreeRTOS-Plus-TCP · Integer Underflow

Affects AWS FreeRTOS-Plus-TCPSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 4.4.1 or 4.2.6 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.4.1, 4.2.6
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade AWS FreeRTOS-Plus-TCP to 4.4.1 or 4.2.6.

Affected software

ProductAffectedFixed in
AWSFreeRTOS-Plus-TCPAffected
  • >=4.3.0 <4.4.1
Fixed in
  • 4.4.1
AWSFreeRTOS-Plus-TCPAffected
  • >=4.0.0 <4.2.6
Fixed in
  • 4.2.6
GitHubfreertos/FreeRTOS-Plus-TCPpkg:github/freertos/FreeRTOS-Plus-TCPOther threatsAffected
  • =4.0.0
  • =4.3.0
Fixed in–
GitHubFreeRTOS-Plus-TCPpkg:github/FreeRTOS-Plus-TCPOther threatsAffected
  • >=4.0.0 <4.2.6
  • >=4.3.0 <4.4.1
Fixed in
  • 4.2.6
  • 4.4.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available from AWS in FreeRTOS-Plus-TCP versions 4.4.1 and 4.2.6. Users should upgrade to these fixed versions to remediate the vulnerability. Since this is a cloud service managed by AWS, the vendor handles remediation for the cloud-hosted components. Refer to the AWS security bulletin at https://aws.amazon.com/security/security-bulletins/2026-021-aws/ for official guidance and updates.

Description

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.

References

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