CyberSecBulletin
CVE-2024-27394NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-27394 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 ca4fb6c6764b3f75b4f5aa81db1536291897ff7f, 80e679b352c3ce5158f3f778cfb77eb767e586fb 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 0.26% 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 ca4fb6c6764b3f75b4f5aa81db1536291897ff7f or 80e679b352c3ce5158f3f778cfb77eb767e586fb, whichever matches your release line, or a later version.
  2. Update linux_kernel to ca4fb6c6764b or 80e679b352c3, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux7c2ffaf21bd67f73d21560995ce17eaf5fc1d37f up to, but not including, ca4fb6c6764b3f75b4f5aa81db1536291897ff7f; 7c2ffaf21bd67f73d21560995ce17eaf5fc1d37f up to, but not including, 80e679b352c3ce5158f3f778cfb77eb767e586fb; 6.7ca4fb6c6764b3f75b4f5aa81db1536291897ff7f, 80e679b352c3ce5158f3f778cfb77eb767e586fb
Linuxlinux_kernel6.7; 7c2ffaf21bd6 up to, but not including, ca4fb6c6764b; 7c2ffaf21bd6 up to, but not including, 80e679b352c3ca4fb6c6764b, 80e679b352c3

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
LowNo special conditions are needed; the attack works reliably.
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:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.4HighCISA (ADP)

Official description

In the Linux kernel, the following vulnerability has been resolved: tcp: Fix Use-After-Free in tcp_ao_connect_init Since call_rcu, which is called in the hlist_for_each_entry_rcu traversal of tcp_ao_connect_init, is not part of the RCU read critical section, it is possible that the RCU grace period will pass during the traversal and the key will be free. To prevent this, it should be changed to hlist_for_each_entry_safe.

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. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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