{"id":"CVE-2026-10634","summary":"Use-after-free in Zephyr native TCP `net_tcp_foreach()` due to dropping `tcp_lock` during the callback","details":"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.","aliases":["GHSA-6c57-xfhw-j26x"],"modified":"2026-10-28T02:59:17.674893747Z","published":"2026-06-15T14:16:43.871Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10634.json","cna_assigner":"zephyr","cwe_ids":["CWE-416"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10634.json"},{"type":"ADVISORY","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6c57-xfhw-j26x"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-10634"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/cd85e0e890ab89815c4cbc0a8fbc03a3efa84dc2"},{"type":"PACKAGE","url":"https://github.com/zephyrproject-rtos/zephyr"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zephyrproject-rtos/zephyr","events":[{"introduced":"468eb56cf242eedba62006ee758700ee6148763f"},{"fixed":"75f67d766726351b30199f9a2bf55803d717a3be"},{"introduced":"684c9e8f32e4373a21098559f748f06915f950c9"},{"fixed":"1f6485eca25431b5ff27ce9a754218c9e559bbbb"},{"fixed":"cd85e0e890ab89815c4cbc0a8fbc03a3efa84dc2"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"3.6.0"},{"fixed":"4.3.1"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"range":[{"introduced":"4.4.0"},{"fixed":"4.4.1"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"range":[{"fixed":"cd85e0e890ab89815c4cbc0a8fbc03a3efa84dc2"}],"source":"REFERENCES_COMMIT"}]}}],"versions":["v4.3.1-rc1","v4.4.1-rc1","v4.4.0","v4.3.0","v4.3.0-rc3","v4.3.0-rc2","v4.3.0-rc1","v4.2.0","v4.2.0-rc3","v4.2.0-rc2","v4.2.0-rc1","v4.1.0","v4.1.0-rc3","v4.1.0-rc2","v4.1.0-rc1","v4.0.0","v4.0.0-rc3","v4.0.0-rc2","v4.0.0-rc1","v3.7.0","v3.7.0-rc3","v3.7.0-rc2","v3.7.0-rc1","v3.6.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-10634.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}