CVE-2026-102714

ICMPv6 option validation accepts a trailing byte residue, sending the Router Advertisement, Neighbor Solicitation, Neighbor Advertisement and Redirect option walkers past the packet or into a permanent loop

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Published Sep 29, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
Description
In Eclipse ThreadX NetX Duo versions up to and including 6.5.2.202603, built with IPv6, the ICMPv6 option validator accepts an option area that ends in a one- or two-byte residue, and the Router Advertisement, Neighbor Solicitation, Neighbor Advertisement and Redirect handlers then walk it without length checks. A host on the local link can send one such message to make the IP thread read past the packet or loop forever, and can place off-packet memory in the neighbor cache.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Description `_nx_icmpv6_validate_options()` scans the option area with `while (length > 2)` (`common/src/nx_icmpv6_validate_options.c:79`). An area whose size leaves a one- or two-byte residue exits the loop with that tail unexamined; the residue is not negative, so the function returns `NX_SUCCESS`. Its zero-length rejection never sees those bytes. Every consumer then re-walks the same area, reading a two-byte option header at the residue and subtracting `nx_icmpv6_option_length << 3` with no zero check and no remaining-length check. Three outcomes follow, selected by bytes the attacker controls. **Zero length byte.** The walker subtracts zero and advances zero. All four handlers loop forever — `_nx_icmpv6_process_ra` (`nx_icmpv6_process_ra.c:245, :528`), `_nx_icmpv6_process_ns` (`:251, :329`), `_nx_icmpv6_process_na` (`:147, :156`) and `_nx_icmpv6_process_redirect` (`:247, :350`). The walk runs in the IP thread, which is the highest-priority thread and does not yield inside the loop, so the system stops until a watchdog reset and the frame can be replayed after each one. **Non-zero length byte on a short residue.** The three unsigned counters underflow — `2 - 8` becomes `0xFFFFFFFA` — and the walk continues past the packet buffer, reading until it faults or meets a zero length byte and freezes. The Router Advertisement counter is signed and exits cleanly in this case. **One-byte residue.** The walker reads a two-byte option header, over-reading one byte. During a runaway walk, stray bytes parsing as a link-layer address option are copied into the neighbor cache (`nx_icmpv6_process_ns.c:280, :293`) and subsequently used as the destination MAC for frames to that neighbour, placing off-packet memory on the link. Confirmed by inspection, not reproduced. In Eclipse ThreadX NetX Duo versions up to and including 6.5.2.202603, built with IPv6, the ICMPv6 option validator accepts an option area that ends in a one- or two-byte residue, and the Router Advertisement, Neighbor Solicitation, Neighbor Advertisement and Redirect handlers then walk it without length checks. A host on the local link can send one such message to make the IP thread read past the packet or loop forever, and can place off-packet memory in the neighbor cache.
Title ICMPv6 Option Validation Bug in NetX Duo Causing Potential Infinite Loop and Denial of Service via Crafted Packets ICMPv6 option validation accepts a trailing byte residue, sending the Router Advertisement, Neighbor Solicitation, Neighbor Advertisement and Redirect option walkers past the packet or into a permanent loop
Type Values Removed Values Added
First Time appeared Eclipse
Eclipse netx Duo
Vendors & Products Eclipse
Eclipse netx Duo
Type Values Removed Values Added
Title ICMPv6 Option Validation Bug in NetX Duo Causing Potential Infinite Loop and Denial of Service via Crafted Packets
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
Description `_nx_icmpv6_validate_options()` scans the option area with `while (length > 2)` (`common/src/nx_icmpv6_validate_options.c:79`). An area whose size leaves a one- or two-byte residue exits the loop with that tail unexamined; the residue is not negative, so the function returns `NX_SUCCESS`. Its zero-length rejection never sees those bytes. Every consumer then re-walks the same area, reading a two-byte option header at the residue and subtracting `nx_icmpv6_option_length << 3` with no zero check and no remaining-length check. Three outcomes follow, selected by bytes the attacker controls. **Zero length byte.** The walker subtracts zero and advances zero. All four handlers loop forever — `_nx_icmpv6_process_ra` (`nx_icmpv6_process_ra.c:245, :528`), `_nx_icmpv6_process_ns` (`:251, :329`), `_nx_icmpv6_process_na` (`:147, :156`) and `_nx_icmpv6_process_redirect` (`:247, :350`). The walk runs in the IP thread, which is the highest-priority thread and does not yield inside the loop, so the system stops until a watchdog reset and the frame can be replayed after each one. **Non-zero length byte on a short residue.** The three unsigned counters underflow — `2 - 8` becomes `0xFFFFFFFA` — and the walk continues past the packet buffer, reading until it faults or meets a zero length byte and freezes. The Router Advertisement counter is signed and exits cleanly in this case. **One-byte residue.** The walker reads a two-byte option header, over-reading one byte. During a runaway walk, stray bytes parsing as a link-layer address option are copied into the neighbor cache (`nx_icmpv6_process_ns.c:280, :293`) and subsequently used as the destination MAC for frames to that neighbour, placing off-packet memory on the link. Confirmed by inspection, not reproduced.
Weaknesses CWE-125
CWE-1287
CWE-191
CWE-835
References
Metrics cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}
Weaknesses

Sources

Status
PUBLISHED
Assigner
eclipse
Published
Updated
Nov 4, 2026, 1:06 PM
Reserved
Sep 29, 2026, 4:15 PM

View source JSON

Updated
Sep 29, 2026, 6:43 PM

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Status
Awaiting Analysis
Published
Sep 29, 2026, 6:17 PM
Modified
Nov 4, 2026, 2:17 PM

View source JSON

No data.

Updated
Nov 4, 2026, 4:00 PM

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