Every day, dozens of new CVEs (Common Vulnerabilities and Exposures) get published. Security teams scan them, prioritize them, and make decisions about remediation. But here's the problem: most people don't actually understand what they're reading.
I've spent years watching organizations make bad decisions based on misinterpreting CVE data. Let's fix that.
The CVE Basics
First, understand what a CVE is and isn't:
A CVE is:
- A unique identifier for a specific vulnerability
- A standardized way to reference security issues
- Assigned by CVE Numbering Authorities (CNAs)
A CVE is not:
- A complete security advisory
- Always accompanied by a patch
- A guarantee the vulnerability is exploitable
The CVE ID format is simple: CVE-YEAR-NUMBER. For example, CVE-2024-1234.
Reading the Description (The Right Way)
The description is often the most misunderstood part. Here's what to look for:
1. The Actual Vulnerability
Look past the jargon. Ask:
- What exactly is broken?
- Under what conditions does this matter?
- What specific versions are affected?
Bad interpretation: "It says buffer overflow, that sounds really bad!"
Good interpretation: "It's a stack buffer overflow in the admin API that requires authentication with administrative privileges and is only exposed on localhost by default."
Context matters enormously.
2. Attack Requirements
Pay attention to phrases like:
- "Requires authentication"
- "Local access required"
- "User interaction required"
- "Default configuration"
These dramatically change risk.
Example: CVE-2024-XXXX might have a CVSS of 9.8 (Critical), but if it requires both:
- Physical access to the device
- Disabling default protections
- Rebooting into a special mode
...then its real-world severity for your environment might be much lower.
3. Impact Specifics
"Code execution" doesn't tell the full story. Ask:
- In what context? (Browser sandbox? Kernel? User-space?)
- With what privileges? (Administrator? Limited user? Service account?)
- On what systems? (Client? Server? Both?)
CVSS Scores: A Helpful Lie
CVSS scores are useful but often misleading. Here's why:
The Formula vs Reality
CVSS uses a mathematical formula based on factors like:
- Attack vector (Network, Adjacent, Local, Physical)
- Attack complexity (Low, High)
- Privileges required (None, Low, High)
- User interaction (None, Required)
- Impact to confidentiality, integrity, availability
But CVSS can't account for:
- Whether the vulnerable component is internet-facing in your environment
- Whether the affected functionality is actually used
- Whether effective mitigations exist
- Whether exploit code is publicly available
- Whether the vulnerability is being actively exploited
Reading Between the Lines
A CVSS 9.8 sounds terrifying, but look at the vector string:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
This tells you:
- AV:N - Network accessible (concerning if internet-facing)
- AC:L - Low complexity (easy to exploit)
- PR:N - No privileges required (accessible to anyone)
- UI:N - No user interaction needed (can be automated)
- S:U - Unchanged scope (doesn't escape security boundaries)
- C:H/I:H/A:H - High impact to confidentiality, integrity, availability
Now compare to another 9.8:
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
That UI:R means user interaction is required. That S:C means scope changed (potentially escaping sandbox). These are very different vulnerabilities despite identical base scores.
What the CVE Doesn't Tell You
Here's what you won't find in most CVEs but desperately need to know:
1. Exploitability
The CVE rarely says:
- Is exploit code publicly available?
- How difficult is exploitation really?
- Have attacks been observed?
You need to check:
- CISA's Known Exploited Vulnerabilities (KEV) catalog
- Threat intelligence feeds
- Security researcher blogs and Twitter
- Exploit databases
2. Real-World Context
CVEs don't tell you:
- How commonly this software is deployed
- What configurations are actually vulnerable
- What alternative mitigations exist
Example: A critical vulnerability in a specific PHP library sounds bad. But if that library is only used by three abandoned WordPress plugins from 2015, your risk is probably minimal.
3. Remediation Options
Most CVEs eventually reference patches, but they don't tell you:
- When patches will be available for all versions
- If patches break anything
- What temporary workarounds exist
- If the vendor actually plans to patch old versions
The Information You Actually Need
For effective risk assessment, gather:
1. Exposure
- Do we even use the affected software/version?
- Is the vulnerable component accessible from the internet?
- What systems have it installed?
2. Exploitability
- Is exploit code public?
- Has exploitation been observed?
- What's the actual exploit complexity?
3. Impact
- What systems are affected?
- What data/services could be compromised?
- What's the business impact of compromise?
4. Mitigations
- Are patches available?
- Can we apply workarounds?
- What's the risk of the patch itself?
Common Misinterpretations
"Critical CVSS = Must Patch Immediately"
Not always. I've seen "critical" CVEs that:
- Affected debugging features disabled in production
- Required multiple prerequisites almost never met
- Were already mitigated by existing controls
"Low CVSS = Can Wait"
Also wrong. Some "low" severity issues:
- Are actively exploited because they're easy
- Chain with other vulnerabilities for major impact
- Affect authentication or authorization
"Published Date = Discovery Date"
Nope. Vulnerabilities might be:
- Discovered years earlier but only recently disclosed
- Under active exploitation before CVE assignment
- Known to attackers but not to vendors
A Better Approach
Here's my actual process for evaluating CVEs:
1. Read the full NVD entry Not just the summary - read everything.
2. Find the vendor advisory Vendors often provide much more context than the CVE.
3. Check CISA KEV If it's there, prioritize it.
4. Search for technical analysis Security researchers often publish detailed breakdowns that reveal the real story.
5. Assess YOUR environment Generic risk scores don't matter - your specific deployment does.
6. Make a decision Patch, mitigate, accept, or defer - with clear reasoning.
Tools That Help
- NVD: Official CVE database with enriched data
- CISA KEV: Known exploited vulnerabilities
- VulnDB: Commercial database with more context
- ExploitDB: Public exploit repository
- Twitter/Mastodon: Security researchers often share insights
- Vendor security pages: First-party information about fixes
The Bottom Line
Reading CVEs is a skill. Don't just look at the score and the description. Understand:
- The technical details of what's actually broken
- The prerequisites for exploitation
- The real-world context for your environment
- Available mitigations and their trade-offs
With practice, you'll get much better at separating the truly critical vulnerabilities from the noise.
And here's the uncomfortable truth: most CVEs won't significantly affect most organizations. The challenge is finding the ones that matter to you.