CyberSecBulletin
CVE-2026-64403NVD status: Modified

Linux: NULL Pointer Dereference

Published Updated By the CyberSecBulletin desk

CVE-2026-64403 is a high-severity NULL pointer dereference vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions cca81b4bc672604a84f6d224a55cc77ec7dee619, f70d4aa88068096f35d73e3a05eff33c0a16b9cd, 7d871e969b941ce25653f7716203a0ea4d07ad4b as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to cca81b4bc672604a84f6d224a55cc77ec7dee619 or f70d4aa88068096f35d73e3a05eff33c0a16b9cd or 7d871e969b941ce25653f7716203a0ea4d07ad4b or 98d93c226bdfaa79bbdd86981921d7f106374225, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 3.17 or 3.19 or 4.5 or 4.10, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, cca81b4bc672604a84f6d224a55cc77ec7dee619; 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, f70d4aa88068096f35d73e3a05eff33c0a16b9cd; 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, 7d871e969b941ce25653f7716203a0ea4d07ad4b; 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, 98d93c226bdfaa79bbdd86981921d7f106374225; 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, 996d3da39899aceb8f4910911a3f19a45a7d9d1b; 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, 73abbaf91aa33da87c008fb62c148ade561bb606; 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, 6b47bdaacfd0045687880177e0987055d8f4765a; 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 up to, but not including, 687617555cedfb74c9e3cb85d759b908dcb17856; and 15 more rangescca81b4bc672604a84f6d224a55cc77ec7dee619, f70d4aa88068096f35d73e3a05eff33c0a16b9cd, 7d871e969b941ce25653f7716203a0ea4d07ad4b, 98d93c226bdfaa79bbdd86981921d7f106374225, 996d3da39899aceb8f4910911a3f19a45a7d9d1b, 73abbaf91aa33da87c008fb62c148ade561bb606
LinuxLinux Kernel3.16.66 up to, but not including, 3.17; 3.18.138 up to, but not including, 3.19; 4.4.178 up to, but not including, 4.5; 4.9.167 up to, but not including, 4.10; 4.14.110 up to, but not including, 4.15; 4.19.33 up to, but not including, 4.20; 5.0.6 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; and 6 more ranges3.17, 3.19, 4.5, 4.10, 4.15, 4.20

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
LowSome restricted data can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H. Scored by CNA.

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: NULL Pointer Dereference

The product dereferences a pointer that it expects to be valid but is NULL.

How developers prevent this class of flaw

  • For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
  • Select a programming language that is not susceptible to these issues.
  • Check the results of all functions that return a value and verify that the value is non-null before acting upon it.

More NULL Pointer Dereference vulnerabilities (CWE-476)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent NULL Pointer Dereference vulnerabilities

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