CyberSecBulletin
CVE-2023-52439NVD status: Modified

Linux: Double Free

Published Updated By the CyberSecBulletin desk

CVE-2023-52439 is a high-severity double 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 3174e0f7de1ba392dc191625da83df02d695b60c, e93da893d52d82d57fc0db2ca566024e0f26ff50, 5e0be1229ae199ebb90b33102f74a0f22d152570 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 0.3% 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 3174e0f7de1ba392dc191625da83df02d695b60c or e93da893d52d82d57fc0db2ca566024e0f26ff50 or 5e0be1229ae199ebb90b33102f74a0f22d152570 or 5cf604ee538ed0c467abe3b4cda5308a6398f0f7, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.19.306 or 5.4.268 or 5.10.209 or 5.15.148, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, 3174e0f7de1ba392dc191625da83df02d695b60c; 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, e93da893d52d82d57fc0db2ca566024e0f26ff50; 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, 5e0be1229ae199ebb90b33102f74a0f22d152570; 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, 5cf604ee538ed0c467abe3b4cda5308a6398f0f7; 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, 17a8519cb359c3b483fb5c7367efa9a8a508bdea; 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, 35f102607054faafe78d2a6994b18d5d9d6e92ad; 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, 913205930da6213305616ac539447702eaa85e41; 57c5f4df0a5a0ee83df799991251e2ee93a5e4e9 up to, but not including, 0c9ae0b8605078eafc3bea053cc78791e97ba2e2; and 3 more ranges3174e0f7de1ba392dc191625da83df02d695b60c, e93da893d52d82d57fc0db2ca566024e0f26ff50, 5e0be1229ae199ebb90b33102f74a0f22d152570, 5cf604ee538ed0c467abe3b4cda5308a6398f0f7, 17a8519cb359c3b483fb5c7367efa9a8a508bdea, 35f102607054faafe78d2a6994b18d5d9d6e92ad
LinuxLinux Kernelafter 4.18.0 up to, but not including, 4.19.306; 4.20.0 up to, but not including, 5.4.268; 5.5.0 up to, but not including, 5.10.209; 5.11.0 up to, but not including, 5.15.148; 5.16.0 up to, but not including, 6.1.74; 6.2.0 up to, but not including, 6.6.13; 6.7.0 up to, but not including, 6.7.1; 4.184.19.306, 5.4.268, 5.10.209, 5.15.148, 6.1.74, 6.6.13

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: uio: Fix use-after-free in uio_open core-1 core-2 ------------------------------------------------------- uio_unregister_device uio_open idev = idr_find() device_unregister(&idev->dev) put_device(&idev->dev) uio_device_release get_device(&idev->dev) kfree(idev) uio_free_minor(minor) uio_release put_device(&idev->dev) kfree(idev) ------------------------------------------------------- In the core-1 uio_unregister_device(), the device_unregister will kfree idev when the idev->dev kobject ref is 1. But after core-1 device_unregister, put_device and before doing kfree, the core-2 may get_device. Then: 1. After core-1 kfree idev, the core-2 will do use-after-free for idev. 2. When core-2 do uio_release and put_device, the idev will be double freed. To address this issue, we can get idev atomic & inc idev reference with minor_lock.

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

The underlying weakness: Double Free

The product calls free() twice on the same memory address.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

More Double Free vulnerabilities (CWE-415)

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 Double Free vulnerabilities

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