VulnerabilityPublished 13 Sep 2026

CVE-2026-15891: zephyrproject zephyr · Memory-safety

Affects zephyrproject zephyrSource CVE Database V5

Compare

Not known to be exploited · CVSS 7.5 High : upgrade to 4.4.2 soon.

Data as of 29 Oct 2026, 07:15 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.4.2

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within 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 13 Sep 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 29 Oct 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 4.4.2.

Affected software

Product	Affected	Fixed in
zephyrprojectzephyr	Affected >=4.1.0 <4.4.2	Fixed in 4.4.2
GitHubzephyr`pkg:github/zephyr`Other threats	Affected >=4.1.0 <4.4.2	Fixed in 4.4.2

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

AI-suggested

A fix is available that correctly assigns the gateway pointer before dereferencing it, preventing the NULL pointer dereference and memory corruption. Users should upgrade affected Zephyr versions to 4.4.2 or later where this issue is resolved. No additional mitigation is required beyond applying the official fix.

Description

CVE-2026-15891 is a memory safety vulnerability in the Zephyr project's MQTT-SN client keepalive handler. The flaw occurs when the client fails to properly handle gateway records after PINGREQ retries are exhausted, leading to a NULL pointer dereference and subsequent memory corruption or kernel panic. This can be triggered remotely by a malicious or compromised MQTT-SN gateway or an attacker impersonating a gateway. The impact is a denial of service on the affected MQTT-SN client. The vulnerability affects Zephyr versions from 4.1.0 up to but not including 4.4.2. A fix is available that correctly assigns the gateway pointer before use.

Impact

The vulnerability allows a remote attacker to cause a denial of service on the affected MQTT-SN client by triggering a NULL pointer dereference and memory corruption or kernel panic. There is no impact on confidentiality or integrity as no attacker-controlled data is written. The denial of service can be induced by a malicious or compromised MQTT-SN gateway or an attacker impersonating a gateway and failing to respond to keepalive PINGREQs.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 21 Sep 2026, 01:04 UTC

Technical details

References

Community reviews

Related threats