CVE-2026-64403

High

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: validate option length before reading conf opt value l2cap_get_conf_opt() derives the option length from the attacker-controlled opt->len field and immediately dereferences opt->val (as u8, get_unaligned_le16() or get_unaligned_le32(), or a raw pointer for the default case) before any caller has confirmed that opt->len bytes are present in the buffer. The callers (l2cap_parse_conf_req(), l2cap_parse_conf_rsp() and l2cap_conf_rfc_get()) only detect a malformed option afterwards, once the running length has gone negative, by which point the out-of-bounds read has already executed. An existing post-hoc length check keeps the garbage value from being consumed, so this is not a data leak in the current control flow. It is still a validate-after-use ordering bug: up to 4 bytes are read past the end of the buffer before it is known to contain them, and it is fragile to future changes in the callers. Fix it at the source. Pass the end of the buffer into l2cap_get_conf_opt() and refuse to touch opt->val unless the full option (header + value) fits. Each caller computes an end pointer once before the loop and checks the return value directly instead of inferring the error from a negative length.

Package Linux Kernel
Published 2026-07-25
Last modified 2026-09-04
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.1

out of 10
High
Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Weakness type

CWE-476

CVE-2026-64403 is a NULL Pointer Dereference vulnerability

What is NULL Pointer Dereference?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. Learn more on MITRE CWE

Affected versions

Linux kernel versions 3.16.66, 3.18.138, 4.4.178, 4.9.167, 4.14.110, 4.19.33, 5.0.6, 5.1 and later are affected. Fixed in 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2 and their respective stable series.

Affected from
≥ 3.16.66 ≥ 3.18.138 ≥ 4.4.178 ≥ 4.9.167 ≥ 4.14.110 ≥ 4.19.33 ≥ 5.0.6 ≥ 5.1
Fixed in
✓ 5.10.261 5.10.x ✓ 5.15.212 5.15.x ✓ 6.1.178 6.1.x ✓ 6.6.145 6.6.x ✓ 6.12.96 6.12.x ✓ 6.18.39 6.18.x ✓ 7.1.4 7.1.x ✓ 7.2

References

8 total
Showing 5 of 8 references View all on NVD

Frequently asked questions

  • What is CVE-2026-64403?

    CVE-2026-64403 is a High severity Linux kernel vulnerability with a CVSS score of 7.1 out of 10 , classified as a NULL Pointer Dereference flaw (CWE-476) . It affects Linux kernel versions from 3.16.66 onward and has been patched in 5.10.261, 5.15.212, 6.1.178 and others. CVE-2026-64403 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-64403?

    CVE-2026-64403 has a CVSS score of 7.1 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H .

  • Is there a patch available for CVE-2026-64403?

    Yes. CVE-2026-64403 has been patched. Fixed versions include 5.10.261, 5.15.212, 6.1.178 and others. If you are running Linux kernel 3.16.66 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-64403 actively exploited?

    No. CVE-2026-64403 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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