CVE-2026-7426: Insufficient validation of the prefix length field in IPv6 Router Advertisement processing in FreeRTOS-Plus-TC

Routine

HIGH 8.1WATCHLISTUPGRADE

CVE-2026-7426 is a high-severity flaw (CVSS 8.1) affecting freertos-plus-tcp. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 ve

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 84%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-04-29
Last modified	2026-10-26

Publisher (CNA): AMZN · Vendor: amazon

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-29 20:16 UTCPublished CVE record published
2026-10-26 20:10 UTCUpdated Record last modified

amazon freertos-plus-tcp UPGRADE

Affected: >= 4.0.0 and < 4.2.6 · >= 4.3.0 and < 4.4.1

Fixed in: 4.2.6, 4.4.1

Safe to downgrade to: a release before 4.0.0

1. Check installed version

apt-cache policy freertos-plus-tcp || rpm -q freertos-plus-tcp || freertos-plus-tcp --version

2. UPGRADE to 4.2.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade freertos-plus-tcp

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade freertos-plus-tcp

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison freertos-plus-tcp sudo apt install freertos-plus-tcp=<VERSION_BEFORE_4.0.0> sudo apt-mark hold freertos-plus-tcp

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list freertos-plus-tcp sudo dnf downgrade freertos-plus-tcp-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add freertos-plus-tcp

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-7426?

freertos-plus-tcp: upgrade to 4.2.6, 4.4.1. Exact commands for each OS are on this page.

Is CVE-2026-7426 being exploited?

CVE-2026-7426 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-7426 affect?

CVE-2026-7426 affects freertos-plus-tcp. Severity is high (CVSS 8.1). 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 w

How urgent is CVE-2026-7426?

Priority 37/100. High severity; On your watchlist

Related CVEs

CVE-2026-7424 HIGH 8.1 UPGRADE Integer underflow in the DHCPv6 sub-option parser in FreeRTOS-Plus-TCP before V4.4.1 and V4.2.6 allows an adja
CVE-2026-7425 MEDIUM 6.5 UPGRADE Insufficient option length validation in the IPv6 Router Advertisement parser in FreeRTOS-Plus-TCP before V4.2
CVE-2026-7422 MEDIUM 6.5 UPGRADE Insufficient packet validation in FreeRTOS-Plus-TCP before V4.2.6 and V4.4.1 allows an adjacent network actor
CVE-2026-7423 MEDIUM 5.3 UPGRADE Integer underflow in the ICMP and ICMPv6 echo reply handlers in FreeRTOS-Plus-TCP before V4.4.1 and V4.2.6 all

References

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