high CVSS 7.1 EPSS <0.1%

CVE-2022-49234·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: net: dsa: Avoid cross-chip syncing of VLAN filtering Changes to VLAN filtering are not applicable to cross-chip notifications. On a system like this: .-----. .-----. .-----. | sw1 +---+ sw2 +---+ sw3 | '-1-2-' '-1-2-' '-1-2-' Before this change, upon sw1p1 leaving a bridge, a call to dsa_port_vlan_filtering would also be made to sw2p1 and sw3p1. In this scenario: .---------. .-----. .-----. | sw1 +---+ sw2 +---+ sw3 | '-1-2-3-4-' '-1-2-' '-1-2-' When sw1p4 would leave a bridge, dsa_port_vlan_filtering would be called for sw2 and sw3 with a non-existing port - leading to array out-of-bounds accesses and crashes on mv88e6xxx.

Severity
high
Software
Kernel
Fixed in
5.17.2
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 12% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2022-49234 scores 7.1 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 5.2

Until: 5.17.2

Fixed in: 5.17.2

How to fix this CVE

Update your Linux kernel to version 5.17.2 or later to resolve a critical issue in the DSA (Distributed Switch Architecture) subsystem that causes cross-chip VLAN filtering notifications to be incorrectly applied to non-existent ports. This vulnerability can lead to kernel memory access violations and system crashes on multi-chip switch topologies. Prioritize this update for systems using network switches with multiple interconnected chips, particularly those running mv88e6xxx drivers.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check your current kernel version: uname -r — compare against the fixed version 5.17.2 and confirm if you are running 5.2 through 5.17.1
  2. Verify if DSA drivers are loaded: lsmod | grep -i dsa — this indicates active use of the distributed switch architecture
  3. Check for mv88e6xxx switch driver: lsmod | grep mv88e6xxx — if present, your system uses the affected hardware
  4. Confirm the fix is applied after update: uname -r should show 5.17.2 or later; additionally verify dmesg | tail -20 shows no VLAN-related array access errors

FAQ

What is CVE-2022-49234?

This is a kernel vulnerability in the DSA (Distributed Switch Architecture) subsystem where VLAN filtering state changes incorrectly propagate across multiple interconnected network switches. When a port on a switch leaves a bridge, the kernel attempts to update VLAN filters on non-existent ports on downstream switches, causing out-of-bounds memory access.

Is CVE-2022-49234 being actively exploited?

No, this vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. However, it can be triggered by legitimate network configuration changes on affected systems.

What versions of Kernel are affected by CVE-2022-49234?

Linux kernel versions 5.2 through 5.17.1 are vulnerable. Version 5.17.2 and later include the fix.

How do I check if my server is vulnerable to CVE-2022-49234?

Run uname -r to check your kernel version; if it shows 5.2.x through 5.17.1, you are vulnerable. Additionally run lsmod | grep dsa to confirm if the DSA subsystem is in use on your system.

Does Defensia detect CVE-2022-49234?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Linux kernel is installed on a monitored server running versions 5.2 through 5.17.1, CVE-2022-49234 will appear in your dashboard with remediation steps.

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References

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