Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
zephyrproject zephyr — Use-after-free in Zephyr native TCP `net_tcp_foreach()` due to dropping `tcp_lock` during the callback
AV AC PR UI S C I A CVSS EPSS %ile KEV
A H N N U N N H 5.3 .0027 19.9 —
AFFECTED
Product Versions Fixed
zephyr 3.6.0 – —
TIMELINE
Jun 2 Reserved by zephyr
Jun 15 EXPLOIT PUBLISHED — CVE-2026-10634 (zephyrproject zephyr). Public exploit reference added.
Jun 15 Published (CNA: zephyr)
Aug 6 EXPLOIT PUBLISHED — CVE-2026-10634 (zephyrproject zephyr). Public exploit reference added.
Aug 6 RESCORED — CVE-2026-10634 (zephyrproject zephyr). CVSS 4.8 → 5.3 (NVD).
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.
During 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).
net_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.
The 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.
Lifecycle
Complete event history — 5 events, chronological
| Date | Event | Detail |
|---|
| June 2, 2026 | Reserved | Reserved by zephyr |
| June 15, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-10634 (zephyrproject zephyr). Public exploit reference added. |
| June 15, 2026 | Published | Published (CNA: zephyr) |
| August 6, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-10634 (zephyrproject zephyr). Public exploit reference added. |
| August 6, 2026 | RESCORED | RESCORED — CVE-2026-10634 (zephyrproject zephyr). CVSS 4.8 → 5.3 (NVD). |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| zephyrproject | zephyr | — | 3.6.0 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-10634 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.