CyberSecBulletin
CVE-2022-3640NVD status: Modified

Kernel: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2022-3640 is a high-severity use after free vulnerability in Kernel from Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 1.21% chance of exploitation within 30 days, higher than 69% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux Kernel to 4.9.333 or 4.14.299 or 4.19.265 or 5.4.224, whichever matches your release line, or a later version.
  2. Read the advisory on git.kernel.org for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxKernelNot specified in the recordNot stated
LinuxLinux Kernel4.9.326 up to, but not including, 4.9.333; 4.14.291 up to, but not including, 4.14.299; 4.19.255 up to, but not including, 4.19.265; 5.4.209 up to, but not including, 5.4.224; 5.10.135 up to, but not including, 5.10.154; 5.15.59 up to, but not including, 5.15.79; 5.18.16 up to, but not including, 6.0.84.9.333, 4.14.299, 4.19.265, 5.4.224, 5.10.154, 5.15.79
Fedora ProjectFedora35; 36; 37Not 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
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
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Scoring systemScoreSeverityScored by
CVSS 3.15.5MediumCNA (vuldb.com)
CVSS 3.18.8HighNVD

Official description

A vulnerability, which was classified as critical, was found in Linux Kernel. Affected is the function l2cap_conn_del of the file net/bluetooth/l2cap_core.c of the component Bluetooth. The manipulation leads to use after free. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-211944.

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

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Kernel

All Kernel vulnerabilities

Recent Use After Free vulnerabilities

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