What is CVE-2026-53209?

CVE-2026-53209 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, classified as a Out-of-bounds Write flaw (CWE-787), affecting Linux kernel versions from 6.1.142 onward and patched in 6.1.176, 6.6.143, 6.12.94 and others. CVE-2026-53209 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-53209?

CVE-2026-53209 has a CVSS score of 7.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2026-53209?

Yes, CVE-2026-53209 has been patched. Fixed versions include 6.1.176, 6.6.143, 6.12.94 and others. If you are running Linux kernel 6.1.142 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-53209 actively exploited?

CVE-2026-53209 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Out-of-bounds Write (CWE-787)?

The product writes data past the end or before the beginning of the intended buffer. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/787.html

CVE-2026-53209

High

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: reject oversized Broadcast Announcement prepend Existing advertising instances can already hold the maximum extended advertising payload. When hci_adv_bcast_annoucement() prepends the Broadcast Announcement service data to that payload, the combined data may no longer fit in the temporary buffer used to rebuild the advertising data. Reject that case before copying the existing payload and report the failure through the device log. This keeps the existing advertising data intact and avoids overrunning the temporary buffer.

Package Linux Kernel

Published 2026-06-25

Last modified 2026-07-02

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Weakness type

CWE-787

CVE-2026-53209 is a Out-of-bounds Write vulnerability

What is Out-of-bounds Write?

The product writes data past the end or before the beginning of the intended buffer. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.1.142, 6.6.94, 6.12.34, 6.15.3, 6.16 and later are affected. Fixed in 6.1.176, 6.6.143, 6.12.94, 6.18.36, 7.0.13, 7.1 and their respective stable series.

Affected from

≥ 6.1.142 ≥ 6.6.94 ≥ 6.12.34 ≥ 6.15.3 ≥ 6.16

Fixed in

✓ 6.1.176 6.1.x ✓ 6.6.143 6.6.x ✓ 6.12.94 6.12.x ✓ 6.18.36 6.18.x ✓ 7.0.13 7.0.x ✓ 7.1

References

6 total

Kernel Git
https://git.kernel.org/stable/c/02f50e8bb69f9b22516163a09922f5537d3b12d1

Patch
Kernel Git
https://git.kernel.org/stable/c/10b0e832cc05d7aef4b92bed912cbd4a395d0862

Patch
Kernel Git
https://git.kernel.org/stable/c/1338ee049a8910ba6c9cee963920e978e6893c7d

Patch
Kernel Git
https://git.kernel.org/stable/c/5c65b96b549ea2dcfde497436bf9e048deb87758

Patch
Kernel Git
https://git.kernel.org/stable/c/cdd8bbdbee763fdf5bf343e6f7d4e79347739f62

Patch

Showing 5 of 6 references View all on NVD

Details

CVE ID CVE-2026-53209

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2026-06-25

Modified 2026-07-02

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-53209?

CVE-2026-53209 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Out-of-bounds Write flaw (CWE-787) . It affects Linux kernel versions from 6.1.142 onward and has been patched in 6.1.176, 6.6.143, 6.12.94 and others. CVE-2026-53209 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-53209?

CVE-2026-53209 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2026-53209?

Yes. CVE-2026-53209 has been patched. Fixed versions include 6.1.176, 6.6.143, 6.12.94 and others. If you are running Linux kernel 6.1.142 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-53209 actively exploited?

No. CVE-2026-53209 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.