Description
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: L2CAP: validate frame length before control and FCS access

l2cap_data_rcv() unpacks either a two-byte or four-byte control field
without first ensuring that it is present. A short ERTM or streaming-mode
frame can therefore cause an out-of-bounds read.

There is a second short-frame case when CRC16 is enabled. After the
control field is pulled, l2cap_check_fcs() subtracts two from skb->len
without checking it. If fewer than two bytes remain, the subtraction
wraps; skb_trim() leaves the buffer unchanged and the subsequent FCS
load reads past the logical end of the frame.

Validate that the frame contains both its control field and, when
enabled, its FCS before either field is accessed.
Published: 2026-10-18
Score: n/a
EPSS: < 1% Very Low
KEV: No
Impact: Out-of-Bounds Read
Action: Patch Kernel
AI Analysis

Impact

The vulnerability lies in the Linux kernel’s Bluetooth L2CAP layer, where the code fails to validate the length of incoming frames before accessing the control field and optional Frame Check Sequence. This omission allows a short frame to trigger an out‑of‑bounds read, potentially exposing kernel memory contents or enabling further exploitation. At its core, the weakness is a classic out‑of‑bounds memory read."

Affected Systems

Linux kernel deployments that include the Bluetooth L2CAP driver are affected. The vulnerability does not specify version constraints, so it is prudent to assume that all kernel branches containing the unpatched code are vulnerable until verified otherwise."

Risk and Exploitability

The flaw permits a crafted Bluetooth packet to cause the kernel to read past the end of the skb buffer, which could lead to information disclosure or a denial of service. While there is no publicly available exploitation kit, a remote attacker with Bluetooth communication privileges can send the malformed packet, making the attack vector likely remote and local to the host’s Bluetooth stack. The EPSS score is unavailable, and the vulnerability is not listed in the CISA KEV catalog, suggesting that it may not yet be widely exploited but remains a legitimate risk.

Generated by OpenCVE AI on October 18, 2026 at 16:49 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Apply the kernel patch that introduces length validation before reading the L2CAP control field and FCS as documented in the referenced git commits
  • Rebuild or upgrade to a Linux kernel release that incorporates these changes, ensuring the patched version is present on all affected hosts
  • If an immediate kernel upgrade is not feasible, disable the L2CAP Bluetooth interface or restrict access to trusted devices until the patch is applied

Generated by OpenCVE AI on October 18, 2026 at 16:49 UTC.

Tracking

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Advisories

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History

Sun, 18 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: validate frame length before control and FCS access l2cap_data_rcv() unpacks either a two-byte or four-byte control field without first ensuring that it is present. A short ERTM or streaming-mode frame can therefore cause an out-of-bounds read. There is a second short-frame case when CRC16 is enabled. After the control field is pulled, l2cap_check_fcs() subtracts two from skb->len without checking it. If fewer than two bytes remain, the subtraction wraps; skb_trim() leaves the buffer unchanged and the subsequent FCS load reads past the logical end of the frame. Validate that the frame contains both its control field and, when enabled, its FCS before either field is accessed.
Title Bluetooth: L2CAP: validate frame length before control and FCS access
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-19T09:19:53.885Z

Reserved: 2026-09-25T10:25:14.350Z

Link: CVE-2026-98457

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-18T16:16:56.110

Modified: 2026-10-19T10:18:55.100

Link: CVE-2026-98457

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-18T23:30:13Z

Weaknesses

No weakness.