CyberSecBulletin
CVE-2023-46838NVD status: Modified

Linux: NULL Pointer Dereference

Published Updated By the CyberSecBulletin desk

CVE-2023-46838 is a high-severity NULL pointer dereference vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 1.18% chance of exploitation within 30 days, higher than 68% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux Kernel to 4.19.306 or 5.4.268 or 5.10.209 or 5.15.148, whichever matches your release line, or a later version.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxNot specified in the recordNot stated
LinuxLinux Kernel4.14 up to, but not including, 4.19.306; 4.20 up to, but not including, 5.4.268; 5.5 up to, but not including, 5.10.209; 5.11 up to, but not including, 5.15.148; 5.16 up to, but not including, 6.1.75; 6.2 up to, but not including, 6.6.14; 6.7 up to, but not including, 6.7.24.19.306, 5.4.268, 5.10.209, 5.15.148, 6.1.75, 6.6.14
Fedora ProjectFedora38; 39Not stated
DebianDebian Linux10.0Not stated

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
NetworkCan be exploited remotely over a network, including the internet.
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
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

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

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighNVD
CVSS 3.17.5HighCISA (ADP)

Official description

Transmit requests in Xen's virtual network protocol can consist of multiple parts. While not really useful, except for the initial part any of them may be of zero length, i.e. carry no data at all. Besides a certain initial portion of the to be transferred data, these parts are directly translated into what Linux calls SKB fragments. Such converted request parts can, when for a particular SKB they are all of length zero, lead to a de-reference of NULL in core networking code.

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: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Third-party and government advisories

Recent NULL Pointer Dereference vulnerabilities

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