# CVE-2026-10682: Out-of-bounds write in Zephyr `log_filter_set` syscall verifier reachable from userspace

Status: published. Published: 2026-07-27. Updated: 2026-11-04.

The userspace verifier z_vrfy_log_filter_set() for the log_filter_set syscall in subsys/logging/log_mgmt.c performed a signed comparison against the int16_t src_id parameter: src_id < (int16_t)log_src_cnt_get(domain_id). Any negative value for src_id (e.g. -1) trivially satisfied this check and was forwarded into z_impl_log_filter_set, where it propagated to filter_set() and ultimately to get_dynamic_filter(), which uses source_id as an unsigned index into the linker-section array &TYPE_SECTION_START(log_dynamic)[source_id].filters.

After implicit conversion through uint32_t, an int16_t -1 becomes 0xFFFFFFFF, indexing log_dynamic far out of bounds and causing the kernel to perform an OOB read and an OOB read-modify-write (LOG_FILTER_SLOT_GET/SET) against memory adjacent to the log_dynamic section.

The written value is a constrained 3-bit log level slot within the targeted 32-bit word, but the target address is attacker-chosen (a small negative offset from log_dynamic) and the write occurs in supervisor mode following a syscall from an unprivileged user thread, providing a kernel memory-corruption / privilege-escalation primitive.

The defect is reachable on any build with CONFIG_USERSPACE=y and CONFIG_LOG_RUNTIME_FILTERING=y. Present from Zephyr v3.3.0 through v4.4.1. The fix replaces the signed bound check with an unsigned comparison: (uint32_t)src_id < log_src_cnt_get(domain_id), which correctly rejects negative inputs.

## 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/56a15114c6acbab2067fe406dc3adda8608f3def

## Affected products and versions

- zephyrproject / zephyr (zephyr): ≥ 3.0.0; < 4.3.1 (affected, semver); ≥ 4.4.0; < 4.4.2 (affected, semver). Source: CNA: zephyr

## Severity and prioritization

- CVSS 3.1: 6.6 (medium); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H; source: CNA: zephyr

- CISA KEV: No listing in collected sources

- EPSS: 0.17% as of 2026-11-03; percentile 6.23%

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

- Weaknesses: CWE-787

## Exploit evidence

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

## References

- https://github.com/zephyrproject-rtos/zephyr/commit/56a15114c6acbab2067fe406dc3adda8608f3def (CNA: zephyr; patch)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6vqh-mg7h-58qh (CNA: zephyr)

## Provenance

- CNA: zephyr: https://www.cve.org/CVERecord?id=CVE-2026-10682; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-10682; retrieved 2026-11-04; source updated Not reported

Revision: 2595b10c20db0f6329d6703b22366f1cbbaf42e17838bfb8cf684ebedc047771

Canonical: https://y2.dev/cve/CVE-2026-10682

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