# CVE-2026-10677: Kernel heap memory leak in `z_vrfy_k_poll()` lets an unprivileged user thread exhaust the kernel resource pool

Status: published. Published: 2026-07-21. Updated: 2026-11-04.

The CONFIG_USERSPACE syscall verifier z_vrfy_k_poll() in kernel/poll.c allocates a kernel-side copy of the user-supplied k_poll_event[] via z_thread_malloc() and then validates each event's object handle. Before this fix, validation used K_OOPS(K_SYSCALL_OBJ(...)) inline inside the loop, which kills the calling thread without freeing events_copy.

A user thread can pass num_events >= 1 with a forged object handle to leak the allocation; because newly spawned user threads inherit the parent's resource_pool (kernel/thread.c), an attacker spawns sacrificial threads to repeat the leak until the shared kernel heap is exhausted. Once depleted, legitimate kernel allocations from that pool (k_queue alloc nodes, k_msgq buffers, future k_poll calls, etc.) fail, causing a system-level denial of service.

The fix replaces each inline K_OOPS with a conditional goto oops_free so the buffer is freed before the thread is killed. Affects Zephyr releases from v1.12.0 (when k_poll was first exposed to user mode) through v4.4.1.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: zephyr) — https://github.com/zephyrproject-rtos/zephyr/commit/8dc7a37bc75402a0a3329397887f32f5fb4da3ad

## Affected products and versions

- zephyrproject / zephyr (zephyr): ≥ 1.12.0; < 4.3.1 (affected, semver); ≥ 4.4.0; < 4.4.2 (affected, semver). Source: CNA: zephyr

## Severity and prioritization

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H; source: CNA: zephyr

- CISA KEV: No listing in collected sources

- EPSS: 0.14% as of 2026-11-03; percentile 3.62%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-401

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/zephyrproject-rtos/zephyr/commit/8dc7a37bc75402a0a3329397887f32f5fb4da3ad (CNA: zephyr; patch)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-r3cc-8wcr-xfj9 (CNA: zephyr)

## Provenance

- CNA: zephyr: https://www.cve.org/CVERecord?id=CVE-2026-10677; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-10677; retrieved 2026-11-04; source updated Not reported

Revision: 262c393b58be760471f608bb0d4a6c4dc7fdc7e617ecc495ff77d53c6f365eb7

Canonical: https://y2.dev/cve/CVE-2026-10677

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