{"id":"CVE-2026-10634","state":"PUBLISHED","title":"Use-after-free in Zephyr native TCP `net_tcp_foreach()` due to dropping `tcp_lock` during the callback","description":"Zephyr's native TCP stack iterates the global connection list in net_tcp_foreach() (subsys/net/ip/tcp.c) using the SYS_SLIST_FOR_EACH_CONTAINER_SAFE macro, which caches a pointer to the next list node. Prior to this fix the function released tcp_lock while invoking the per-connection callback and re-acquired it afterwards.\n\nDuring that window a concurrent tcp_conn_release(), running on the dedicated TCP work-queue thread when a connection's reference count drops to zero (e.g. a remote peer closing or resetting the connection), can remove and k_mem_slab_free() the cached next connection. When the iterator advances it dereferences the freed (and possibly reallocated) slab memory — a use-after-free that can crash the system (denial of service) and, if the slot has been reused, cause the callback to operate on an attacker-influenced object (potential information disclosure or further fault).\n\nnet_tcp_foreach() is reached in production via the net conn network shell command and via net_tcp_close_all_for_iface() on interface-down; the freeing side is driven by ordinary TCP traffic.\n\nThe fix moves the connection/context teardown in tcp_conn_release() inside the tcp_lock critical section and keeps tcp_lock held across the callback in net_tcp_foreach(). The defect was introduced with the modern (TCP2) stack in 2020 and affects releases up to and including v4.4.0.","publishedAt":"2026-06-15T14:16:43.871Z","updatedAt":"2026-10-15T22:09:59.383Z","severity":{"score":4.8,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","source":"zephyr"},"assigner":"zephyr","products":["zephyrproject zephyr"],"affected":[{"vendor":"zephyrproject","product":"zephyr","packageName":"zephyr","defaultStatus":"unaffected","versions":[{"version":"3.6.0","status":"affected","lessThan":"4.3.1","versionType":"semver"},{"version":"4.4.0","status":"affected","lessThan":"4.4.1","versionType":"semver"}],"collectionURL":"https://github.com/zephyrproject-rtos/zephyr","programFiles":["subsys/net/ip/tcp.c"]}],"references":["https://github.com/zephyrproject-rtos/zephyr/commit/cd85e0e890ab89815c4cbc0a8fbc03a3efa84dc2","https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6c57-xfhw-j26x"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:10:33.477Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/10xxx/CVE-2026-10634.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-10634","state":"PUBLISHED","datePublished":"2026-06-15T14:16:43.871Z","dateUpdated":"2026-10-15T22:09:59.383Z","assignerShortName":"zephyr","assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","dateReserved":"2026-06-02T15:10:50.607Z"},"containers":{"cna":{"title":"Use-after-free in Zephyr native TCP `net_tcp_foreach()` due to dropping `tcp_lock` during the callback","descriptions":[{"lang":"en","value":"Zephyr's native TCP stack iterates the global connection list in net_tcp_foreach() (subsys/net/ip/tcp.c) using the SYS_SLIST_FOR_EACH_CONTAINER_SAFE macro, which caches a pointer to the next list node. Prior to this fix the function released tcp_lock while invoking the per-connection callback and re-acquired it afterwards.\n\nDuring that window a concurrent tcp_conn_release(), running on the dedicated TCP work-queue thread when a connection's reference count drops to zero (e.g. a remote peer closing or resetting the connection), can remove and k_mem_slab_free() the cached next connection. When the iterator advances it dereferences the freed (and possibly reallocated) slab memory — a use-after-free that can crash the system (denial of service) and, if the slot has been reused, cause the callback to operate on an attacker-influenced object (potential information disclosure or further fault).\n\nnet_tcp_foreach() is reached in production via the net conn network shell command and via net_tcp_close_all_for_iface() on interface-down; the freeing side is driven by ordinary TCP traffic.\n\nThe fix moves the connection/context teardown in tcp_conn_release() inside the tcp_lock critical section and keeps tcp_lock held across the callback in net_tcp_foreach(). The defect was introduced with the modern (TCP2) stack in 2020 and affects releases up to and including v4.4.0."}],"affected":[{"vendor":"zephyrproject","product":"zephyr","packageName":"zephyr","defaultStatus":"unaffected","versions":[{"version":"3.6.0","status":"affected","lessThan":"4.3.1","versionType":"semver"},{"version":"4.4.0","status":"affected","lessThan":"4.4.1","versionType":"semver"}],"collectionURL":"https://github.com/zephyrproject-rtos/zephyr","programFiles":["subsys/net/ip/tcp.c"]}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/cd85e0e890ab89815c4cbc0a8fbc03a3efa84dc2","name":"Fix commit","tags":["patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6c57-xfhw-j26x","name":"GHSA-6c57-xfhw-j26x"}],"metrics":[{"cvssV3_1":{"baseScore":4.8,"baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","description":"use-after-free","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"zephyr","orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","dateUpdated":"2026-10-15T22:09:59.383Z"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-15T16:06:39.217653Z","id":"CVE-2026-10634","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-15T16:06:49.600Z"}}]}}}