CyberSecBulletin
CVE-2022-3636NVD status: Modified

Kernel: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2022-3636 is a high-severity use after free vulnerability in Kernel from 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. Affected Kernel versions: 33fc42de33278b2b3ec6f3390512987bc29a62b7. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.36% 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. Check which version of Kernel you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on git.kernel.org for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxKernel33fc42de33278b2b3ec6f3390512987bc29a62b7Not stated
LinuxLinux KernelNot specified in the recordNot stated
DebianDebian Linux11.0Not stated

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 4.05.1MediumCNA (vuldb.com)
CVSS 3.15.5MediumCNA (vuldb.com)
CVSS 3.17.8HighNVD
CVSS 2.04.9MediumCNA (vuldb.com)

Official description

A vulnerability was identified in Linux Kernel 33fc42de33278b2b3ec6f3390512987bc29a62b7. This affects the function __mtk_ppe_check_skb of the file drivers/net/ethernet/mediatek/mtk_ppe.c of the component Ethernet Handler. Such manipulation leads to use after free. The name of the patch is 17a5f6a78dc7b8db385de346092d7d9f9dc24df6. It is best practice to apply a patch to resolve this issue. No released Linux Kernel version was ever affected by this CVE.

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: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Kernel

All Kernel vulnerabilities

Recent Use After Free vulnerabilities

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