CyberSecBulletin
CVE-2022-42720NVD status: Modified

SIMATIC S7-1500 TM MFP - GNU/Linux subsystem: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2022-42720 is a high-severity use after free vulnerability in SIMATIC S7-1500 TM MFP - GNU/Linux subsystem from Siemens, 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 version V1.1 as the first without the flaw, so updating SIMATIC S7-1500 TM MFP - GNU/Linux subsystem to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.9% chance of exploitation within 30 days, higher than 60% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update SIMATIC S7-1500 TM MFP - GNU/Linux subsystem to V1.1 or a later version.
  2. Update Linux Kernel to 5.4.218 or 5.10.148 or 5.15.74 or 5.19.16, whichever matches your release line, or a later version.
  3. Read the advisory on git.kernel.org for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystembefore V1.1V1.1
LinuxLinux Kernel5.1 up to, but not including, 5.4.218; 5.5 up to, but not including, 5.10.148; 5.11 up to, but not including, 5.15.74; 5.16 up to, but not including, 5.19.16; 6.0 up to, but not including, 6.0.25.4.218, 5.10.148, 5.15.74, 5.19.16, 6.0.2
Fedora ProjectFedora36; 37Not stated
DebianDebian Linux10.0; 11.0Not 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 3.17.8HighNVD
CVSS 3.17.8HighCISA (ADP)

Official description

Various refcounting bugs in the multi-BSS handling in the mac80211 stack in the Linux kernel 5.1 through 5.19.x before 5.19.16 could be used by local attackers (able to inject WLAN frames) to trigger use-after-free conditions to potentially execute code.

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: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Technical write-ups (may include proof of concept)

Other vulnerabilities in SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

All SIMATIC S7-1500 TM MFP - GNU/Linux subsystem vulnerabilities

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