CyberSecBulletin
CVE-2023-4622NVD status: Modified

Kernel: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2023-4622 is a high-severity use after free vulnerability in Kernel from Linux, with a CVSS 3.1 base score of 7.0 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 4.14.324, 4.19.293, 5.4.255 as the first without the flaw, so updating Kernel to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.62% chance of exploitation within 30 days, higher than 50% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Kernel to 4.14.324 or 4.19.293 or 5.4.255 or 5.10.192, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.14.324 or 4.19.293 or 5.4.255 or 5.10.192, whichever matches your release line, or a later version.
  3. Read the advisory on git.kernel.org for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxKernel4.2 up to, but not including, 4.14.324; 4.15 up to, but not including, 4.19.293; 4.20 up to, but not including, 5.4.255; 5.5 up to, but not including, 5.10.192; 5.11 up to, but not including, 5.15.128; 5.16 up to, but not including, 6.1.47; 6.2 up to, but not including, 6.4.124.14.324, 4.19.293, 5.4.255, 5.10.192, 5.15.128, 6.1.47
LinuxLinux Kernel4.2 up to, but not including, 4.14.324; 4.15 up to, but not including, 4.19.293; 4.20 up to, but not including, 5.4.255; 5.5 up to, but not including, 5.10.192; 5.11 up to, but not including, 5.15.128; 5.16 up to, but not including, 6.1.47; 6.2 up to, but not including, 6.4.124.14.324, 4.19.293, 5.4.255, 5.10.192, 5.15.128, 6.1.47
DebianDebian Linux10.0; 12.0Not 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
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
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:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA (google.com)
CVSS 3.17.0HighNVD

Official description

A use-after-free vulnerability in the Linux kernel's af_unix component can be exploited to achieve local privilege escalation. The unix_stream_sendpage() function tries to add data to the last skb in the peer's recv queue without locking the queue. Thus there is a race where unix_stream_sendpage() could access an skb locklessly that is being released by garbage collection, resulting in use-after-free. We recommend upgrading past commit 790c2f9d15b594350ae9bca7b236f2b1859de02c (or backported equivalents).

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

Other vulnerabilities in Kernel

All Kernel vulnerabilities

Recent Use After Free vulnerabilities

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