CyberSecBulletin
CVE-2022-50386NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2022-50386 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 8.0 out of 10. It can be exploited from the same local network by an attacker with a low-privileged account, without any action from a user. The record lists versions 11e40d6c0823f699d8ad501e48d1c3ae4be386cd, 843fc4e386dd84b806a7f07fb062d8c3a44e5364, d91fc2836562f299f34e361e089e9fe154da4f73 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 0.37% 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 11e40d6c0823f699d8ad501e48d1c3ae4be386cd or 843fc4e386dd84b806a7f07fb062d8c3a44e5364 or d91fc2836562f299f34e361e089e9fe154da4f73 or 7d6f9cb24d2b2f6b6370eac074e2e6b1bafdad45, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.9.331 or 4.14.296 or 4.19.262 or 5.4.220, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 11e40d6c0823f699d8ad501e48d1c3ae4be386cd; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 843fc4e386dd84b806a7f07fb062d8c3a44e5364; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, d91fc2836562f299f34e361e089e9fe154da4f73; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 7d6f9cb24d2b2f6b6370eac074e2e6b1bafdad45; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 0c108cf3ad386e0084277093b55a351c49e0be27; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, d1e894f950ad48897d1a7cb05909ea29d8c3810e; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 6ffde6e03085874ae22263ff4cef4869f797e84f; 3df91ea20e744344100b10ae69a17211fcf5b207 up to, but not including, 15fc21695eb606bdc5d483b92118ee42610a952d; and 2 more ranges11e40d6c0823f699d8ad501e48d1c3ae4be386cd, 843fc4e386dd84b806a7f07fb062d8c3a44e5364, d91fc2836562f299f34e361e089e9fe154da4f73, 7d6f9cb24d2b2f6b6370eac074e2e6b1bafdad45, 0c108cf3ad386e0084277093b55a351c49e0be27, d1e894f950ad48897d1a7cb05909ea29d8c3810e
LinuxLinux Kernelbefore 4.9.331; 4.10 up to, but not including, 4.14.296; 4.15 up to, but not including, 4.19.262; 4.20 up to, but not including, 5.4.220; 5.5 up to, but not including, 5.10.150; 5.11 up to, but not including, 5.15.75; 5.16 up to, but not including, 5.19.17; 6.0 up to, but not including, 6.0.34.9.331, 4.14.296, 4.19.262, 5.4.220, 5.10.150, 5.15.75

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
AdjacentThe attacker must be on the same local network segment.
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:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCNA
CVSS 3.18.0HighNVD
CVSS 3.18.0HighCISA (ADP)

Official description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix user-after-free This uses l2cap_chan_hold_unless_zero() after calling __l2cap_get_chan_blah() to prevent the following trace: Bluetooth: l2cap_core.c:static void l2cap_chan_destroy(struct kref *kref) Bluetooth: chan 0000000023c4974d Bluetooth: parent 00000000ae861c08 ================================================================== BUG: KASAN: use-after-free in __mutex_waiter_is_first kernel/locking/mutex.c:191 [inline] BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:671 [inline] BUG: KASAN: use-after-free in __mutex_lock+0x278/0x400 kernel/locking/mutex.c:729 Read of size 8 at addr ffff888006a49b08 by task kworker/u3:2/389

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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