VulnerabilityPublished 19 Jul 2026Updated 13 Aug 2026

CVE-2026-64127: Linux kernel · Bluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer

Source GCVE Database

Not known to be exploited · CVSS 5.5 Medium.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score

5.5Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
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: 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: 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 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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.

ghsa-w532-m3j8-f99h

What to do

AI-suggested

A fix has been implemented in the Linux kernel to correct the size and pointer arguments passed to l2cap_send_cmd() in the ecred_reconfigure function, restoring the proper transmission of the request payload and preventing kernel stack address leakage. Users should apply the official Linux kernel patch that addresses this issue. Patch status is not explicitly confirmed in the provided data; therefore, check the vendor advisory or Linux kernel mailing lists for the current remediation guidance and updated kernel versions containing the fix.

Description

A vulnerability in the Linux kernel Bluetooth L2CAP implementation caused a kernel stack address to be leaked to a paired Bluetooth peer due to incorrect handling of a packed protocol data unit (PDU) in the ecred_reconfigure function. This issue resulted from a code change that altered the data structure used without adjusting size and pointer arguments, causing the kernel to send unintended stack pointer data instead of the expected request fields. The flaw breaks the L2CAP_ECRED_RECONFIGURE feature for the local initiator and leaks kernel stack information, potentially aiding attackers in bypassing kernel address space layout randomization (KASLR).

Impact

The vulnerability leaks kernel stack memory addresses to a paired Bluetooth peer, which can aid in bypassing kernel address space layout randomization (KASLR) protections. The flaw does not impact confidentiality or integrity directly but causes the L2CAP_ECRED_RECONFIGURE feature to malfunction, resulting in denial of service for that feature on the local initiator side. There is no indication of remote code execution or privilege escalation from this issue. No known exploits are reported in the wild.

Summary

The vulnerability CVE-2026-64127 in the Linux kernel's Bluetooth L2CAP subsystem arises from an incorrect update to the ecred_reconfigure function. A commit replaced an explicit packed struct with a DEFINE_RAW_FLEX macro but failed to update the size and source-pointer arguments passed to l2cap_send_cmd(). As a result, the function sent 8 bytes from the kernel stack representing the pointer's address rather than the intended 6-byte request payload (mtu, mps, scid). This causes a kernel stack address leak to the paired Bluetooth device and breaks the L2CAP_ECRED_RECONFIGURE feature for the local initiator. The issue was fixed by restoring the original semantics, passing the correct size and pointer to the payload. The vulnerability has a CVSS 3.1 base score of 5.5 (medium severity) with local attack vector, low privileges required, no user interaction, and an impact on availability only.

References

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