CyberSecBulletin
CVE-2023-52872NVD status: Modified

Linux: Concurrent Execution using Shared Resource with Improper Synchronization

Published Updated By the CyberSecBulletin desk

CVE-2023-52872 is a high-severity concurrent execution using shared resource with improper synchronization 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 81a4dd5e6c78f5d8952fa8c9d36565db1fe01444, df6cfab66ff2a44bd23ad5dd5309cb3421bb6593, 19d34b73234af542cc8a218cf398dee73cdb1890 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 0.18% 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 81a4dd5e6c78f5d8952fa8c9d36565db1fe01444 or df6cfab66ff2a44bd23ad5dd5309cb3421bb6593 or 19d34b73234af542cc8a218cf398dee73cdb1890 or ce4df90333c4fe65acb8b5089fdfe9b955ce976a, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.138 or 5.19 or 6.1.62 or 6.5.11, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxdd37f657387853623f20c1b2482afbb9cd8ece33 up to, but not including, 81a4dd5e6c78f5d8952fa8c9d36565db1fe01444; c568f7086c6e771c77aad13d727c70ef70e07243 up to, but not including, df6cfab66ff2a44bd23ad5dd5309cb3421bb6593; c568f7086c6e771c77aad13d727c70ef70e07243 up to, but not including, 19d34b73234af542cc8a218cf398dee73cdb1890; c568f7086c6e771c77aad13d727c70ef70e07243 up to, but not including, ce4df90333c4fe65acb8b5089fdfe9b955ce976a; c568f7086c6e771c77aad13d727c70ef70e07243 up to, but not including, 3a75b205de43365f80a33b98ec9289785da56243; d834aba5f30d9a6f98f4ca1eb07e501f1989331c; 692e847a8e6607909c4a3f98ab16ccee7849bd11; 5.15.61 up to, but not including, 5.15.138; and 3 more ranges81a4dd5e6c78f5d8952fa8c9d36565db1fe01444, df6cfab66ff2a44bd23ad5dd5309cb3421bb6593, 19d34b73234af542cc8a218cf398dee73cdb1890, ce4df90333c4fe65acb8b5089fdfe9b955ce976a, 3a75b205de43365f80a33b98ec9289785da56243, 5.15.138
LinuxLinux Kernel5.15.61 up to, but not including, 5.15.138; 5.18.18 up to, but not including, 5.19; 5.19.2 up to, but not including, 6.1.62; 6.2 up to, but not including, 6.5.11; 6.6 up to, but not including, 6.6.15.15.138, 5.19, 6.1.62, 6.5.11, 6.6.1

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 3.15.5MediumCISA (ADP)

Official description

In the Linux kernel, the following vulnerability has been resolved: tty: n_gsm: fix race condition in status line change on dead connections gsm_cleanup_mux() cleans up the gsm by closing all DLCIs, stopping all timers, removing the virtual tty devices and clearing the data queues. This procedure, however, may cause subsequent changes of the virtual modem status lines of a DLCI. More data is being added the outgoing data queue and the deleted kick timer is restarted to handle this. At this point many resources have already been removed by the cleanup procedure. Thus, a kernel panic occurs. Fix this by proving in gsm_modem_update() that the cleanup procedure has not been started and the mux is still alive. Note that writing to a virtual tty is already protected by checks against the DLCI specific connection state.

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

The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How developers prevent this class of flaw

  • In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
  • Use thread-safe capabilities such as the data access abstraction in Spring.
  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

More Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities (CWE-362)

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

Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities

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