嚴重 CVE 剛公佈：MSP 在首 48 小時應採取的行動

It happens a few times a year. A vulnerability in a VPN appliance, a firewall, a file-transfer tool or a widely used library gets announced, it's rated critical, and within hours there are reports of attacks. Clients start emailing. Your team wants to know where to start.

The MSPs that handle these well aren't faster typists. They follow the same short routine every time.

Hour 0 to 4: confirm what you're dealing with

Before touching anything, answer four questions from reliable sources (the vendor advisory, the CVE record, and CISA if it has commented):

1. What exactly is affected? Product, versions and configurations. Many critical flaws only apply when a specific feature is turned on.
2. Is it being exploited? Check whether it's on CISA's Known Exploited Vulnerabilities catalog, and look at its EPSS score, which estimates how likely exploitation is in the next 30 days.
3. Is it reachable from the internet? An internet-facing VPN portal and an internal-only admin console are very different emergencies.
4. Is there a fix or a workaround? A patched version, a configuration change, or a vendor mitigation to apply until the patch is out.

Write the answers down in a short internal note. It becomes the basis for everything you tell clients.

Hour 4 to 12: find out who's exposed

This is where good asset data pays off. Work from what you already have:

• Your RMM and asset inventory: search for the product and version across every client
• Your latest scan exports: filter by the product name, CPE or affected port
• A targeted rescan: many scanners publish a check for a high-profile CVE quickly; run it against the likely systems rather than waiting for the monthly scan
• External exposure: check which clients have the affected service open to the internet

The output you want is a simple list: client, system, version, internet-facing or not, and whether a fix is available.

Hour 12 to 24: fix in order of exposure

Not every affected system needs the same urgency. A sensible order:

1. Internet-facing systems where exploitation has been confirmed
2. Other internet-facing systems
3. Internal systems that hold sensitive data or admin access
4. Everything else, inside the normal patch cycle

Where a patch isn't available yet, apply the vendor's mitigation, restrict access to the affected service, or take it offline briefly if the client agrees. For edge devices that were exposed before you patched, check the vendor's guidance on signs of compromise, because patching alone doesn't remove an attacker who is already in.

Hour 24 to 48: confirm and tell clients

Patching isn't finished until you've checked it worked. Rescan the affected systems, or verify the version directly, and note the result.

Then send each affected client a short update. Clients who weren't affected appreciate a note too:

"Yesterday a critical vulnerability was announced in [product]. We checked all of your systems. Two were affected; both were updated last night and we've confirmed the fix. No action is needed from you."

Three sentences, no jargon, and a clear answer to the only question they have: are we OK?

Afterwards: keep the lessons

Once things are quiet, spend twenty minutes on what slowed you down. Usually it's one of three things: an asset that wasn't in the inventory, a client whose scans hadn't run recently, or a device nobody had admin access to. Fix that gap and the next one goes faster.

Varaxon Scan Hub reads exports from the scanners you already use and turns them into clear, client-ready reports, with known exploited vulnerabilities at the top. Your first 3 reports are free, no credit card needed: varaxontech.com.

Related: CVSS vs EPSS vs CISA KEV · Vulnerability remediation SLAs

Drafted with AI assistance and reviewed by the Varaxon team.