CVE-2026-12364
The user-space system-call verifier z_vrfy_z_log_msg_static_create() in subsys/logging/log_msg.c was a pure pass-through: it forwarded the caller-supplied source, desc, package, and data arguments directly to the kernel-mode implementation z_impl_z_log_msg_static_create() without performing any of the mandatory K_SYSCALL_* checks. Because z_log_msg_static_create() is declared __syscall, under CONFIG_USERSPACE any unprivileged user-mode thread can invoke it directly with fully attacker-controlled arguments. The kernel-mode handler dereferences each of these untrusted values: frontend_runtime_filtering() reads through the source pointer as a struct log_source_dynamic_data, cbprintf_package_copy() reads desc.package_len bytes from the package pointer, and z_log_msg_finalize() performs a memcpy() of desc.data_len bytes from the data pointer. With no verification, a user thread can supply arbitrary kernel addresses and arbitrary lengths, and the kernel will read from them. The impact is a kernel-mode denial of service (the kernel faults dereferencing an attacker-chosen pointer) and, where a log backend output is observable to the attacker, disclosure of arbitrary kernel memory copied into the emitted log message — a confidentiality breach across the user/kernel boundary that the userspace sandbox is meant to enforce. The reads do not corrupt kernel memory, so there is no out-of-bounds write primitive. The fix adds the required validation to the verifier: it bounds desc.package_len against Z_LOG_MSG_MAX_PACKAGE, rejects non-NULL/length mismatches, and applies K_SYSCALL_MEMORY_READ() to package, data, and (when runtime filtering with a frontend is enabled) source, so any out-of-bounds or kernel pointer now raises K_OOPS instead of being honored.
Executive briefing
The source record describes: The user-space system-call verifier z_vrfy_z_log_msg_static_create() in subsys/logging/log_msg.c was a pure pass-through: it forwarded the caller-supplied source, desc, package, and data arguments directly to the kernel-mode implementation z_impl_z_log_msg_static_create() without performing any of the mandatory K_SYSCALL_* checks. Because z_log_msg_static_create() is declared __syscall, under CONFIG_USERSPACE any unprivileged user-mode thread can invoke it directly with fully attacker-controlled arguments. The kernel-mode handler dereferences each of these untrusted values: frontend_runtime_filtering() reads through the source pointer as a struct log_source_dynamic_data, cbprintf_package_copy() reads desc.package_len bytes from the package pointer, and z_log_msg_finalize() performs a memcpy() of desc.data_len bytes from the data pointer. With no verification, a user thread can supply arbitrary kernel addresses and arbitrary lengths, and the kernel will read from them. The impact is a kernel-mode denial of service (the kernel faults dereferencing an attacker-chosen pointer) and, where a log backend output is observable to the attacker, disclosure of arbitrary kernel memory copied into the emitted log message — a confidentiality breach across the user/kernel boundary that the userspace sandbox is meant to enforce. The reads do not corrupt kernel memory, so there is no out-of-bounds write primitive. The fix adds the required validation to the verifier: it bounds desc.package_len against Z_LOG_MSG_MAX_PACKAGE, rejects non-NULL/length mismatches, and applies K_SYSCALL_MEMORY_READ() to package, data, and (when runtime filtering with a frontend is enabled) source, so any out-of-bounds or kernel pointer now raises K_OOPS instead of being honored. The practical risk depends on whether an affected product/version is present, reachable and configured in an exploitable way. Review the affected-product evidence and linked vendor advisories before assigning exposure status.
Evidence confidence: Limited Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:H
Technical explanation & impact
The technical mechanism is not expanded beyond the source description unless a referenced advisory supplies additional evidence. Read the linked vendor/CERT advisories for root-cause detail.
Potential impact must be interpreted from the published CVSS impact metrics and the affected component. A CVSS impact score is not proof that a particular asset is exploitable.
Weakness classification
CWE-822Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
- https://github.com/zephyrproject-rtos/zephyr/commit/77aa26d8b940f39778154f02563caf15d02efdac VENDOR vulnerabilities@zephyrproject.org
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-h7rf-g9mg-g23f VENDOR vulnerabilities@zephyrproject.org
Information gaps & confidence notes
These gaps indicate missing source data. CVE Watch does not fill them with guessed product, exploit or patch details.
- NVD does not currently provide machine-readable vulnerable CPE product/version entries for this record.
Last enrichment: 2026-11-05T05:08:22+00:00 · Source last modified: 2026-11-04T05:18:39.043