Heap out-of-bounds write via unchecked RA prefix length
Published Apr 29, 2026 · Updated Apr 29, 2026
Out-of-bounds write in FreeRTOS-Plus-TCP 4.0.0 through 4.2.5 and 4.3.0 through 4.4.0 allows attackers to corrupt memory via IPv6 RAs. The IPv6 Router Advertisement option parser accepts a prefix-length value above the protocol maximum and uses it in memory operations without checking the destination buffer bounds. A device on the local network can trigger the heap overwrite without authentication or user interaction, but deployments that process only IPv4 Router Advertisements are unaffected.
Summary
What happened
Out-of-bounds write in FreeRTOS-Plus-TCP 4.0.0 through 4.2.5 and 4.3.0 through 4.4.0 allows attackers to corrupt memory via IPv6 RAs. The IPv6 Router Advertisement option parser accepts a prefix-length value above the protocol maximum and uses it in memory operations without checking the destination buffer bounds. A device on the local network can trigger the heap overwrite without authentication or user interaction, but deployments that process only IPv4 Router Advertisements are unaffected.
The record
- CVE
- CVE-2026-7426
- Published
- Apr 29, 2026
- Updated
- Apr 29, 2026
- Vendor
- Amazon Web Services
- Product
- FreeRTOS-Plus-TCP
- Classifications
- CWE-787
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 29, 2026CVE publishedPublication date reported by the CVE source.
- Apr 29, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.0.0 <4.2.6
- Affected versionversion=4.3.0 <4.4.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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