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CVE-2026-74540

Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp

CVSS score

8.8

EPSS probability

%0.3

Risk score

0.0

Published

2 mo ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Official patch verified

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Vulnerability description

DayBreach CVE AI Research

CVE-2026-74540 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp l2cap_le_connect_rsp() obtains a channel via __l2cap_get_chan_by_ident() but neither holds a reference nor uses l2cap_chan_hold_unless_zero() before locking and operating on it. A concurrent l2cap_chan_del() triggered by a remote disconnect can free the channel between the lookup and l2cap_chan_lock(), causing a use-after-free. The BR/EDR counterpart l2cap_connect_rsp() and the sibling handler l2cap_le_command_rej() already use l2cap_chan_hold_unless_zero() to safely hold a reference, but l2cap_le_connect_rsp() was left unprotected. Fix by adding l2cap_chan_hold_unless_zero() after the ident lookup and l2cap_chan_put() on the exit path, consistent with other L2CAP response handlers.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-74540 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1linuxLinux View
2linuxLinux View
Total affected vendors: 1|Products: 2

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
8.8CVSS V31HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HNVD
8.8CVSS V3_1HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVE CNA
5.3CVSS 3.x—CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HMicrosoft MSRC

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

1 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

reference

Yama veya çözüm referansı

Open source
Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-74540 is associated with the following CWEs:

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')CWE-20: Improper Input Validation

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-74540 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureBitişik ağ
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

https://git.kernel.org/stable/c/15d6c2367217a6a20b1abae9f38ded716bf620f1vendor-advisoryhttps://git.kernel.org/stable/c/1818180fe12d6cec7a437bc59cde8efdf6b10250vendor-advisoryhttps://git.kernel.org/stable/c/8325eafb38c3dee5af329266393763693d17381bvendor-advisoryhttps://git.kernel.org/stable/c/fd4c1e301bdec60a40728ea37de531cbccda501avendor-advisoryhttps://git.kernel.org/stable/c/522b730c62c53a1981604fd73524697fd347830dvendor-advisoryhttps://git.kernel.org/stable/c/58e3c5289ad230a7e24ae4b0c7b43f5ee6e32136vendor-advisoryhttps://git.kernel.org/stable/c/09f447accc2570751e7d17f0dc0788b40d3edadevendor-advisoryhttps://git.kernel.org/stable/c/c4740e7f23ff9a8210198d8b4703259e21b9f69dvendor-advisoryhttps://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgradepatch

CVSS Vector Radar Chart

8.8 / 10
Attack VectorAdjacentComplexityLowPrivilegesNoneUser Interact.NoneConfidentialityLowIntegrityNoneAvailabilityHigh

Vulnerability Scoring Details

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack VectorAdjacent network
Attack ComplexityLow
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)None
Availability (Erişilebilirlik)High

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