CyberSecBulletin
CVE-2023-6535NVD status: Modified

Red Hat Enterprise Linux 8: NULL Pointer Dereference

Published Updated By the CyberSecBulletin desk

CVE-2023-6535 is a high-severity NULL pointer dereference vulnerability in Red Hat Enterprise Linux 8 from Red Hat, 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 1.55% chance of exploitation within 30 days, higher than 75% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Red Hat Enterprise Linux 8 you run against the affected versions below, and install the vendor's latest release.
  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
Red HatRed Hat Enterprise Linux 8Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.6 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.8 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.2 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat Virtualization 4 for Red Hat Enterprise Linux 8Not specified in the recordNot stated
Red HatRHOL-5.8-RHEL-9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 6Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 7Not specified in the recordNot stated
LinuxLinux KernelNot specified in the recordNot stated
Red HatCodeready Linux Builder EUS8.6; 9.2Not stated
Red HatCodeready Linux Builder EUS For Power Little Endian EUS8.6_ppc64le; 9.2_ppc64leNot stated
Red HatCodeready Linux Builder For Arm64 EUS8.6_aarch64; 9.2_aarch64Not stated
Red HatCodeready Linux Builder For IBM Z Systems EUS9.2_s390xNot stated
Red HatEnterprise Linux8.0; 9.0Not stated
Red HatEnterprise Linux EUS8.6; 9.2Not stated
Red HatEnterprise Linux For Arm 64 EUS8.6_aarch64; 9.2_aarch64Not stated
Red HatEnterprise Linux For IBM Z Systems EUS8.6_s390x; 9.2_s390xNot stated
Red HatEnterprise Linux For Power Little Endian EUS8.6_ppc64le; 9.2_ppc64leNot stated
Red HatEnterprise Linux For Real Time9.2Not stated
Red HatEnterprise Linux For Real Time For Nfv9.2Not stated
Red HatEnterprise Linux Server AUS8.6; 9.2Not stated
Red HatEnterprise Linux Server For Power Little Endian Update Services For SAP Solutions8.6_ppc64le; 9.2_ppc64leNot stated
Red HatEnterprise Linux Server TUS8.6Not stated
Red HatVirtualization Host4.0Not 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 3.16.5MediumCNA (redhat.com)
CVSS 3.17.5HighNVD

Official description

A flaw was found in the Linux kernel's NVMe driver. This issue may allow an unauthenticated malicious actor to send a set of crafted TCP packages when using NVMe over TCP, leading the NVMe driver to a NULL pointer dereference in the NVMe driver, causing kernel panic and a denial of service.

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

Third-party and government advisories

Other vulnerabilities in Red Hat Enterprise Linux 8

All Red Hat Enterprise Linux 8 vulnerabilities

Recent NULL Pointer Dereference vulnerabilities

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