Any host on the LAN can send two mDNS records and make the responder write past the end of its
transmit packet.
The string table stores each name in a slot rounded up to a multiple of four:
```c
/* addons/mdns/nxd_mdns.c:11436, 11443, 11447 */
memory_len = ((memory_len & 0xFFFFFFFC) + 8) & 0xFFFFFFFF;
...
len = *((USHORT*)(p - 2)); /* slot size, not string length */
if ((len == memory_len) && ... _nx_mdns_name_match(start, memory_ptr, memory_size) ...)
```
The lookup that decides whether an incoming name is already stored compares the rounded slot size,
so names of 12, 13, 14 and 15 characters share one bucket. A second name in the bucket is answered
with the pointer to the first, and the record then carries a string up to three bytes longer than
the length the caller accounted for. `_nx_mdns_packet_rr_add` (nxd_mdns.c:8911) sizes its only
bound check from that stale length, and `_nx_mdns_name_string_encode` writes the real string.
Two PTR records are enough, both ordinary mDNS responses to a `_http._tcp` query, with owner names
whose lengths fall in the same bucket:
```
==87491==ERROR: AddressSanitizer: heap-buffer-overflow
WRITE of size 1 at 0x611000000124 thread T5
#0 _nx_mdns_name_string_encode addons/mdns/nxd_mdns.c:13096 #1 _nx_mdns_packet_rr_add addons/mdns/nxd_mdns.c:89110x611000000124 is 0 bytes to the right of 228-byte region
```
The overflow is one to three bytes of attacker-influenced name data past `nx_packet_data_end`. In a
normal pool that lands in the next packet in the same pool rather than in a redzone, so the visible
effect is a corrupted neighbouring packet or a corrupted pool free list rather than a clean crash.
Compare the slot size against the stored string length before declaring a match, or keep the
string length in the slot header and return it to the caller so the encoder and the bound check
agree.
"}],"value":"Any host on the LAN can send two mDNS records and make the responder write past the end of its\n\n\n\ntransmit packet.\n\n\n\nThe string table stores each name in a slot rounded up to a multiple of four:\n\n\n\n```c\n\n\n\n/* addons/mdns/nxd_mdns.c:11436, 11443, 11447 */\n\n\n\nmemory_len = ((memory_len & 0xFFFFFFFC) + 8) & 0xFFFFFFFF;\n\n\n\n...\n\n\n\nlen = *((USHORT*)(p - 2)); /* slot size, not string length */\n\n\n\nif ((len == memory_len) && ... _nx_mdns_name_match(start, memory_ptr, memory_size) ...)\n\n\n\n```\n\n\n\nThe lookup that decides whether an incoming name is already stored compares the rounded slot size,\n\n\n\nso names of 12, 13, 14 and 15 characters share one bucket. A second name in the bucket is answered\n\n\n\nwith the pointer to the first, and the record then carries a string up to three bytes longer than\n\n\n\nthe length the caller accounted for. `_nx_mdns_packet_rr_add` (nxd_mdns.c:8911) sizes its only\n\n\n\nbound check from that stale length, and `_nx_mdns_name_string_encode` writes the real string.\n\n\n\nTwo PTR records are enough, both ordinary mDNS responses to a `_http._tcp` query, with owner names\n\n\n\nwhose lengths fall in the same bucket:\n\n\n\n```\n\n\n\n==87491==ERROR: AddressSanitizer: heap-buffer-overflow\n\n\n\nWRITE of size 1 at 0x611000000124 thread T5\n\n #0 _nx_mdns_name_string_encode addons/mdns/nxd_mdns.c:13096\n #1 _nx_mdns_packet_rr_add addons/mdns/nxd_mdns.c:8911\n\n\n0x611000000124 is 0 bytes to the right of 228-byte region\n\n\n\n```\n\n\n\nThe overflow is one to three bytes of attacker-influenced name data past `nx_packet_data_end`. In a\n\n\n\nnormal pool that lands in the next packet in the same pool rather than in a redzone, so the visible\n\n\n\neffect is a corrupted neighbouring packet or a corrupted pool free list rather than a clean crash.\n\n\n\nCompare the slot size against the stored string length before declaring a match, or keep the\n\n\n\nstring length in the slot header and return it to the caller so the encoder and the bound check\n\n\n\nagree."}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"ADJACENT","baseScore":7.1,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","description":"CWE-787 Out-of-bounds Write","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-09-29T17:42:35.719Z","orgId":"e51fbebd-6053-4e49-959f-1b94eeb69a2c","shortName":"eclipse"},"references":[{"url":"https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-2gf7-5224-5vrj"}],"source":{"discovery":"UNKNOWN"},"title":"mDNS string-cache lookup matches on slot size, so a peer name aliases a shorter one and the response encoder writes past the packet","x_generator":{"engine":"Vulnogram 1.0.5"}}},"cveMetadata":{"assignerOrgId":"e51fbebd-6053-4e49-959f-1b94eeb69a2c","assignerShortName":"eclipse","cveId":"CVE-2026-102715","datePublished":"2026-09-29T17:42:35.719Z","dateReserved":"2026-09-29T16:15:11.235Z","dateUpdated":"2026-09-29T18:42:21.812Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-29 18:17:10","lastModifiedDate":"2026-09-29 19:17:20","problem_types":["CWE-787","CWE-787 CWE-787 Out-of-bounds Write"],"metrics":{"cvssMetricV40":[{"source":"emo@eclipse.org","type":"Secondary","cvssData":{"version":"4.0","vectorString":"CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","baseScore":7.1,"baseSeverity":"HIGH","attackVector":"ADJACENT","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-29T18:41:47.412014Z","id":"CVE-2026-102715","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"102715","Ordinal":"1","Title":"mDNS string-cache lookup matches on slot size, so a peer name al","CVE":"CVE-2026-102715","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"102715","Ordinal":"1","NoteData":"Any host on the LAN can send two mDNS records and make the responder write past the end of its\n\n\n\ntransmit packet.\n\n\n\nThe string table stores each name in a slot rounded up to a multiple of four:\n\n\n\n```c\n\n\n\n/* addons/mdns/nxd_mdns.c:11436, 11443, 11447 */\n\n\n\nmemory_len = ((memory_len & 0xFFFFFFFC) + 8) & 0xFFFFFFFF;\n\n\n\n...\n\n\n\nlen = *((USHORT*)(p - 2)); /* slot size, not string length */\n\n\n\nif ((len == memory_len) && ... _nx_mdns_name_match(start, memory_ptr, memory_size) ...)\n\n\n\n```\n\n\n\nThe lookup that decides whether an incoming name is already stored compares the rounded slot size,\n\n\n\nso names of 12, 13, 14 and 15 characters share one bucket. A second name in the bucket is answered\n\n\n\nwith the pointer to the first, and the record then carries a string up to three bytes longer than\n\n\n\nthe length the caller accounted for. `_nx_mdns_packet_rr_add` (nxd_mdns.c:8911) sizes its only\n\n\n\nbound check from that stale length, and `_nx_mdns_name_string_encode` writes the real string.\n\n\n\nTwo PTR records are enough, both ordinary mDNS responses to a `_http._tcp` query, with owner names\n\n\n\nwhose lengths fall in the same bucket:\n\n\n\n```\n\n\n\n==87491==ERROR: AddressSanitizer: heap-buffer-overflow\n\n\n\nWRITE of size 1 at 0x611000000124 thread T5\n\n #0 _nx_mdns_name_string_encode addons/mdns/nxd_mdns.c:13096\n #1 _nx_mdns_packet_rr_add addons/mdns/nxd_mdns.c:8911\n\n\n0x611000000124 is 0 bytes to the right of 228-byte region\n\n\n\n```\n\n\n\nThe overflow is one to three bytes of attacker-influenced name data past `nx_packet_data_end`. In a\n\n\n\nnormal pool that lands in the next packet in the same pool rather than in a redzone, so the visible\n\n\n\neffect is a corrupted neighbouring packet or a corrupted pool free list rather than a clean crash.\n\n\n\nCompare the slot size against the stored string length before declaring a match, or keep the\n\n\n\nstring length in the slot header and return it to the caller so the encoder and the bound check\n\n\n\nagree.","Type":"Description","Title":"mDNS string-cache lookup matches on slot size, so a peer name al"}]}}}