VulnerabilityPublished 3 Apr 2026Updated 19 Oct 2026

CVE-2026-31393: Linux kernel · Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 8.1 High · fixed in e7ff754e339e3d5ce29aa9f95352d0186df8fbd9 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score

8.1High

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

EPSS

0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch

Available – fixed in e7ff754e339e3d5ce29aa9f95352d0186df8fbd9, dd815e6e3918dc75a49aaabac36e4f024d675101, db2872d054e467810078e2b9f440a5b326a601b2 +5

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

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
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: 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: 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: 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 3 Apr 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.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 4e8402a3f884427f9233ba436459c158d1f2e114, < e7ff754e339e3d5ce29aa9f95352d0186df8fbd9	Fixed in e7ff754e339e3d5ce29aa9f95352d0186df8fbd9
LinuxLinux	Affected ≥ 4e8402a3f884427f9233ba436459c158d1f2e114, < dd815e6e3918dc75a49aaabac36e4f024d675101	Fixed in dd815e6e3918dc75a49aaabac36e4f024d675101
LinuxLinux	Affected ≥ 4e8402a3f884427f9233ba436459c158d1f2e114, < db2872d054e467810078e2b9f440a5b326a601b2	Fixed in db2872d054e467810078e2b9f440a5b326a601b2
LinuxLinux	Affected ≥ 4e8402a3f884427f9233ba436459c158d1f2e114, < 5229e7d15771eac2b5886bfb1f976aea0c1eec14	Fixed in 5229e7d15771eac2b5886bfb1f976aea0c1eec14
LinuxLinux	Affected ≥ 4e8402a3f884427f9233ba436459c158d1f2e114, < 807bd1258453c4c83f6ae9dbc1e7b44860ff40d0	Fixed in 807bd1258453c4c83f6ae9dbc1e7b44860ff40d0
LinuxLinux	Affected ≥ 4e8402a3f884427f9233ba436459c158d1f2e114, < 187e6fe939295be36063a1d91f8bebee04399a8c	Fixed in 187e6fe939295be36063a1d91f8bebee04399a8c

AI-suggested

This vulnerability has been fixed in multiple Linux kernel commits as listed in the established facts. Users and administrators should update their Linux kernel to a version that includes these fixes. Since this is not a cloud service, manual patching is required. No additional mitigations are specified by the vendor advisory.

Description

CVE-2026-31393 is a high-severity vulnerability in the Linux kernel's Bluetooth L2CAP implementation. It involves improper validation of the L2CAP_INFO_RSP payload length before accessing data, leading to out-of-bounds reads. Specifically, truncated L2CAP_INFO_RSP packets can cause the kernel to read beyond the intended buffer, potentially causing denial of service or other impacts. The issue is fixed in several Linux kernel commits.

Impact

An attacker can send a specially crafted truncated L2CAP_INFO_RSP packet that triggers out-of-bounds reads in the kernel memory. This can lead to denial of service (kernel crash) or potentially other impacts due to memory corruption. The CVSS score of 8.1 reflects high severity with high confidentiality impact and high availability impact, but no integrity impact. There is no known exploitation in the wild at this time.

Summary

The vulnerability in the Linux kernel Bluetooth L2CAP layer occurs because the function l2cap_information_rsp() verifies that the command length covers the fixed header but does not sufficiently check the payload length before accessing rsp->data. This leads to out-of-bounds reads when processing truncated L2CAP_INFO_RSP packets with result L2CAP_IR_SUCCESS. The flaw affects the handling of feature mask and fixed channel data fields, which require additional length checks. The fix adds payload length validation to prevent unsafe reads and ensures the connection state machine completes safely without stalling.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 12:52 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

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