VulnerabilityPublished 4 Nov 2026

CVE-2026-16511: zephyrproject zephyr · Memory-safety

Affects zephyrproject zephyrSource CVE Database V5

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Not known to be exploited · CVSS 8.8 High : upgrade to 4.5.0 or 4.3.2 soon.

Data as of 4 Nov 2026, 06:28 UTC

CVSS 3.1 base score

8.8High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (zephyr)	CVSS 3.1	8.8

Patch: Available – fixed in 4.5.0, 4.3.2

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Changed
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade zephyrproject zephyr to 4.5.0 or 4.3.2.

Affected software

Product	Affected	Fixed in
zephyrprojectzephyr	Affected >=4.4.0 <4.5.0	Fixed in 4.5.0
zephyrprojectzephyr	Affected >=3.4.0 <4.3.2	Fixed in 4.3.2
GitHubzephyr`pkg:github/zephyr`Other threats	Affected >=3.4.0 <4.3.2 >=4.4.0 <4.5.0	Fixed in 4.3.2 4.5.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Fixed versions 4.3.2 and 4.5.0 of Zephyr are available and should be applied to remediate this vulnerability. The fixes validate user pointers properly, enforce permission checks on RTIO contexts, and bind cancel handles appropriately. Systems built without CONFIG_USERSPACE or CONFIG_RTIO are not affected. Users should upgrade to these fixed versions to mitigate the risk.

Description

CVE-2026-16511 is a memory-safety vulnerability in the Zephyr RTOS affecting the RTIO syscall verifiers. It allows user-mode threads with certain permissions to write to arbitrary kernel memory addresses by exploiting insufficient validation of user-supplied pointers. This can lead to privilege escalation and unauthorized cancellation of I/O submissions. The issue affects Zephyr versions from 3.4.0 up to but not including 4.3.2, and from 4.4.0 up to but not including 4.5.0. Fixed versions are 4.3.2 and 4.5.0.

Impact

Successful exploitation allows a user-mode thread to write arbitrary bits into kernel memory, potentially modifying kernel data structures such as object permissions or thread states. This can lead to privilege escalation from user mode to higher privileges, unauthorized cancellation of I/O submissions belonging to other contexts, and disruption of kernel operations. The vulnerability has a high severity with a CVSS 3.1 score of 8.8, indicating high impact on confidentiality, integrity, and availability.

Summary

The vulnerability arises from two RTIO syscall verifiers in Zephyr that fail to properly validate user-supplied pointers before kernel writes. Specifically, z_vrfy_rtio_sqe_cancel() does not validate the struct rtio_sqe pointer, allowing any user-mode thread in a CONFIG_USERSPACE build to set bits in kernel memory arbitrarily, potentially escalating privileges. Additionally, z_vrfy_rtio_sqe_copy_in_get_handles() only performs a NULL check on a handle out-parameter without verifying write permissions, enabling a user thread with a granted RTIO context to write kernel pointers to arbitrary addresses. The fixes include validating the handle out-parameter as writable, binding cancel handles to real submission-pool storage, and enforcing permission checks on the RTIO context owning the pool. Systems without CONFIG_USERSPACE or CONFIG_RTIO are not affected.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2026, 06:16 UTC

Technical details

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