CyberSecBulletin
CVE-2023-53608NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2023-53608 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 034cce77d52ba013ce62b4f5258c29907eb1ada5, 0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc, 613bf23c070d11c525268f2945aa594704a9b764 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 0.15% 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 034cce77d52ba013ce62b4f5258c29907eb1ada5 or 0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc or 613bf23c070d11c525268f2945aa594704a9b764 or f32297dba338dc06d62286dedb3cdbd5175b1719, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.14.313 or 4.19.281 or 5.4.241 or 5.10.178, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, 034cce77d52ba013ce62b4f5258c29907eb1ada5; 9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, 0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc; 9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, 613bf23c070d11c525268f2945aa594704a9b764; 9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, f32297dba338dc06d62286dedb3cdbd5175b1719; 9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, 92684e02654c91a61a0b0561433b710bcece19fe; 9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, bae009a2f1b7c2011d2e92d8c84868d315c0b97e; 9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, b4d80bd6370b81a1725b6b8f7894802c23a14e9f; 9ff05123e3bfbb1d2b68ba1d9bf1f7d1dffc1453 up to, but not including, 6be49d100c22ffea3287a4b19d7639d259888e33; and 1 more ranges034cce77d52ba013ce62b4f5258c29907eb1ada5, 0dbf0e64b91ee8fcb278aea93eb06fc7d56ecbcc, 613bf23c070d11c525268f2945aa594704a9b764, f32297dba338dc06d62286dedb3cdbd5175b1719, 92684e02654c91a61a0b0561433b710bcece19fe, bae009a2f1b7c2011d2e92d8c84868d315c0b97e
LinuxLinux Kernel2.6.30 up to, but not including, 4.14.313; 4.15 up to, but not including, 4.19.281; 4.20 up to, but not including, 5.4.241; 5.5 up to, but not including, 5.10.178; 5.11 up to, but not including, 5.15.107; 5.16 up to, but not including, 6.1.24; 6.2 up to, but not including, 6.2.11; 6.34.14.313, 4.19.281, 5.4.241, 5.10.178, 5.15.107, 6.1.24

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 NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread() The finalization of nilfs_segctor_thread() can race with nilfs_segctor_kill_thread() which terminates that thread, potentially causing a use-after-free BUG as KASAN detected. At the end of nilfs_segctor_thread(), it assigns NULL to "sc_task" member of "struct nilfs_sc_info" to indicate the thread has finished, and then notifies nilfs_segctor_kill_thread() of this using waitqueue "sc_wait_task" on the struct nilfs_sc_info. However, here, immediately after the NULL assignment to "sc_task", it is possible that nilfs_segctor_kill_thread() will detect it and return to continue the deallocation, freeing the nilfs_sc_info structure before the thread does the notification. This fixes the issue by protecting the NULL assignment to "sc_task" and its notification, with spinlock "sc_state_lock" of the struct nilfs_sc_info. Since nilfs_segctor_kill_thread() does a final check to see if "sc_task" is NULL with "sc_state_lock" locked, this can eliminate the race.

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

Recent Use After Free vulnerabilities

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