VulnerabilityPublished 4 Nov 2026

CVE-2026-85036: zephyrproject zephyr · Memory-safety

Affects zephyrproject zephyrSource CVE Database V5

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Not known to be exploited · CVSS 5.7 Medium : upgrade to 4.5.0 or 4.3.2 when convenient.

Data as of 4 Nov 2026, 06:28 UTC

CVSS 3.1 base score

5.7Medium

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	5.7

Patch: Available – fixed in 4.5.0, 4.3.2

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

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: Low
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: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
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: 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 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 >=4.3.0 <4.3.2	Fixed in 4.3.2
GitHubzephyr`pkg:github/zephyr`Other threats	Affected >=4.3.0 <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

A fix is available and included in Zephyr versions 4.3.2 and 4.5.0. Both commits addressing the issue must be applied together to fully remediate the vulnerability. Users should upgrade affected Zephyr versions to 4.3.2 or 4.5.0 or later. No additional mitigation is required if the fix is applied.

Description

CVE-2026-85036 is a memory-safety vulnerability in the Zephyr project's Bluetooth Classic AVDTP layer affecting versions 4.3.0 up to but not including 4.3.2 and 4.4.0 up to but not including 4.5.0. The flaw arises from improper handling of session stream endpoints during connection reuse, leading to corruption of the system work queue's pending list. This corruption can cause the system work queue to stop processing work or enter a spin loop, resulting in a device-wide denial of service that requires a reboot. The vulnerability affects builds with CONFIG_BT_CLASSIC and CONFIG_BT_A2DP enabled. A two-commit fix is available in versions 4.3.2 and 4.5.0 that must be applied together to fully remediate the issue.

Impact

This vulnerability causes corruption of the system work queue's pending list, leading to either a halt in work processing or an infinite spin loop. The result is a device-wide denial of service that requires a reboot to recover. There is no confidentiality or integrity impact, and no attacker-controlled memory corruption or code execution is possible. Exploitation requires a paired and bonded Bluetooth BR/EDR device to send specific L2CAP signalling commands.

Summary

The vulnerability in Zephyr's Bluetooth Classic AVDTP layer involves deferred releasing of a session's stream endpoints where the embedded work struct remains queued while the session memory is re-initialized and reused. This leads to truncation and corruption of the global system work queue's pending list, either causing the queue to silently stop processing or spin indefinitely. The flaw is deterministic due to the priority and scheduling of Bluetooth RX and system work queues. Exploitation requires a paired/bonded BR/EDR device to send a crafted L2CAP signalling PDU with a disconnection followed by a connection request, triggering the reuse path with pending release work still queued. The impact is a denial of service requiring device reboot, with no direct memory corruption or code execution. The fix involves adding checks to prevent reuse while release work is pending and skipping reuse in the upper A2DP layer, implemented in Zephyr versions 4.3.2 and 4.5.0.

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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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