CyberSecBulletin
CVE-2023-53484NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2023-53484 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 981f339d2905b6a92ef59358158b326493aecac5, d1308bd0b24cb1d78fa2747d5fa3e055cc628a48, cc2d2b3dbfb0ba57bc027fb7e1121250c50e4000 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 0.16% 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 981f339d2905b6a92ef59358158b326493aecac5 or d1308bd0b24cb1d78fa2747d5fa3e055cc628a48 or cc2d2b3dbfb0ba57bc027fb7e1121250c50e4000 or f748e15253833b771acbede14ea98f50831ac289, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.14.316 or 4.19.284 or 5.4.244 or 5.10.181, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, 981f339d2905b6a92ef59358158b326493aecac5; 896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, d1308bd0b24cb1d78fa2747d5fa3e055cc628a48; 896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, cc2d2b3dbfb0ba57bc027fb7e1121250c50e4000; 896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, f748e15253833b771acbede14ea98f50831ac289; 896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, c6ed54dd90698dc0744d669524cc1c122ded8a16; 896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, c9115f49cf260d24d8b5f2d9a4b63cb31a627bb4; 896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, 67bca5f1d644f4e79b694abd8052a177de81c37f; 896f97ea95c1d29c0520ee0766b66b7f64cb967c up to, but not including, 4e0473f1060aa49621d40a113afde24818101d37; and 1 more ranges981f339d2905b6a92ef59358158b326493aecac5, d1308bd0b24cb1d78fa2747d5fa3e055cc628a48, cc2d2b3dbfb0ba57bc027fb7e1121250c50e4000, f748e15253833b771acbede14ea98f50831ac289, c6ed54dd90698dc0744d669524cc1c122ded8a16, c9115f49cf260d24d8b5f2d9a4b63cb31a627bb4
LinuxLinux Kernel3.8.1 up to, but not including, 4.14.316; 4.15 up to, but not including, 4.19.284; 4.20 up to, but not including, 5.4.244; 5.5 up to, but not including, 5.10.181; 5.11 up to, but not including, 5.15.113; 5.16 up to, but not including, 6.1.30; 6.2 up to, but not including, 6.3.4; 3.84.14.316, 4.19.284, 5.4.244, 5.10.181, 5.15.113, 6.1.30

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: lib: cpu_rmap: Avoid use after free on rmap->obj array entries When calling irq_set_affinity_notifier() with NULL at the notify argument, it will cause freeing of the glue pointer in the corresponding array entry but will leave the pointer in the array. A subsequent call to free_irq_cpu_rmap() will try to free this entry again leading to possible use after free. Fix that by setting NULL to the array entry and checking that we have non-zero at the array entry when iterating over the array in free_irq_cpu_rmap(). The current code does not suffer from this since there are no cases where irq_set_affinity_notifier(irq, NULL) (note the NULL passed for the notify arg) is called, followed by a call to free_irq_cpu_rmap() so we don't hit and issue. Subsequent patches in this series excersize this flow, hence the required fix.

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: none, 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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