EUVD-2026-54225

Contiki-NG's DNS/mDNS resolver skipname in os/services/resolv/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attack...

CVE-2026-5855

Contiki-NG's LwM2M TLV parser lwm2mtlvread in os/services/lwm2m/lwm2m-tlv.c ignores its caller-supplied buffer length argument and reads up to six bytes from the input buffer with no bounds check. The caller in lwm2m-engine.c iterates while there is at least one byte remaining, so a crafted CoAP...

CVE-2026-5857

Contiki-NG's MQTT client parsepublishvhdr in os/net/app-layer/mqtt/mqtt.c sets topiclenreceived=1 before checking topiclen against the 64-byte limit, so an over-length topic returns early but leaves the flag set. On the next TCP segment, tcpinput re-invokes the parser with topicreceived==0, and t...

CVE-2026-5856

Contiki-NG's DNS/mDNS resolver skipname in os/services/resolv/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attack...

CVE-2026-5857

The CVE-2026-5857 entry documents a bug in Contiki-NG’s MQTT client, where parse_publish_vhdr() sets topic_len_received=1 before validating topic_len against the 64-byte limit. On the next TCP segment, a persisted flag causes the parser to bypass the guard and perform a memcpy() using an unvalida...

CVE-2026-5857 Contiki-NG MQTT Client Out-of-Bounds Write in PUBLISH Topic Parser via Persistent State Between TCP Segments

Contiki-NG's MQTT client parsepublishvhdr in os/net/app-layer/mqtt/mqtt.c sets topiclenreceived=1 before checking topiclen against the 64-byte limit, so an over-length topic returns early but leaves the flag set. On the next TCP segment, tcpinput re-invokes the parser with topicreceived==0, and t...

CVE-2026-5857 Contiki-NG MQTT Client Out-of-Bounds Write in PUBLISH Topic Parser via Persistent State Between TCP Segments

Contiki-NG's MQTT client parsepublishvhdr in os/net/app-layer/mqtt/mqtt.c sets topiclenreceived=1 before checking topiclen against the 64-byte limit, so an over-length topic returns early but leaves the flag set. On the next TCP segment, tcpinput re-invokes the parser with topicreceived==0, and t...

CVE-2026-5857 Contiki-NG MQTT Client Out-of-Bounds Write in PUBLISH Topic Parser via Persistent State Between TCP Segments

Contiki-NG's MQTT client parsepublishvhdr in os/net/app-layer/mqtt/mqtt.c sets topiclenreceived=1 before checking topiclen against the 64-byte limit, so an over-length topic returns early but leaves the flag set. On the next TCP segment, tcpinput re-invokes the parser with topicreceived==0, and t...

CVE-2026-5856 Contiki-NG DNS/mDNS Resolver Out-of-Bounds Read via Unchecked skip_name Traversal Before Transaction-ID Validation

Contiki-NG's DNS/mDNS resolver skipname in os/services/resolv/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attack...

CVE-2026-5856 Contiki-NG DNS/mDNS Resolver Out-of-Bounds Read via Unchecked skip_name Traversal Before Transaction-ID Validation

Contiki-NG's DNS/mDNS resolver skipname in os/services/resolv/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attack...

CVE-2026-5856

Contiki-NG's DNS/mDNS resolver skipname in os/services/resolv/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attack...

CVE-2026-5856 Contiki-NG DNS/mDNS Resolver Out-of-Bounds Read via Unchecked skip_name Traversal Before Transaction-ID Validation

Contiki-NG's DNS/mDNS resolver skipname in os/services/resolv/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attack...

CVE-2026-5856

Affected software/component: Contiki-NG DNS/mDNS resolver (os/services/resolv/resolv.c). Root cause: skip_name() walks DNS wire-format labels without a packet-boundary check; newdata() loops nquestions from attacker-controlled DNS header before validating the transaction ID, causing the function ...

CVE-2026-5855

Contiki-NG: LwM2M TLV parser in os/services/lwm2m/lwm2m-tlv.c (function lwm2m_tlv_read) ignores the caller’s buffer length and may read up to six bytes without bounds checks. The engine loop continues while bytes remain, so a crafted CoAP WRITE to any LwM2M endpoint whose final TLV supplies exact...

CVE-2026-5855 Contiki-NG LwM2M TLV Parser Out-of-Bounds Read via Unchecked Buffer Length in lwm2m_tlv_read

Contiki-NG's LwM2M TLV parser lwm2mtlvread in os/services/lwm2m/lwm2m-tlv.c ignores its caller-supplied buffer length argument and reads up to six bytes from the input buffer with no bounds check. The caller in lwm2m-engine.c iterates while there is at least one byte remaining, so a crafted CoAP...

CVE-2026-5855 Contiki-NG LwM2M TLV Parser Out-of-Bounds Read via Unchecked Buffer Length in lwm2m_tlv_read

Contiki-NG's LwM2M TLV parser lwm2mtlvread in os/services/lwm2m/lwm2m-tlv.c ignores its caller-supplied buffer length argument and reads up to six bytes from the input buffer with no bounds check. The caller in lwm2m-engine.c iterates while there is at least one byte remaining, so a crafted CoAP...

CVE-2026-5855

Contiki-NG's LwM2M TLV parser lwm2mtlvread in os/services/lwm2m/lwm2m-tlv.c ignores its caller-supplied buffer length argument and reads up to six bytes from the input buffer with no bounds check. The caller in lwm2m-engine.c iterates while there is at least one byte remaining, so a crafted CoAP...

CVE-2026-5855 Contiki-NG LwM2M TLV Parser Out-of-Bounds Read via Unchecked Buffer Length in lwm2m_tlv_read

Contiki-NG's LwM2M TLV parser lwm2mtlvread in os/services/lwm2m/lwm2m-tlv.c ignores its caller-supplied buffer length argument and reads up to six bytes from the input buffer with no bounds check. The caller in lwm2m-engine.c iterates while there is at least one byte remaining, so a crafted CoAP...

CVE-2026-5855: Out-of-bounds Read

Contiki-NG's LwM2M TLV parser lwm2mtlvread in os/services/lwm2m/lwm2m-tlv.c ignores its caller-supplied buffer length argument and reads up to six bytes from the input buffer with no bounds check. The caller in lwm2m-engine.c iterates while there is at least one byte remaining, so a crafted CoAP...

CVE-2026-5857: Out-of-bounds Write

Contiki-NG's MQTT client parsepublishvhdr in os/net/app-layer/mqtt/mqtt.c sets topiclenreceived=1 before checking topiclen against the 64-byte limit, so an over-length topic returns early but leaves the flag set. On the next TCP segment, tcpinput re-invokes the parser with topicreceived==0, and t...