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Introduction:
The National Vulnerability Database (NVD) has long served as the cybersecurity industry’s canonical source for vulnerability intelligence, but a staggering 263% surge in CVE submissions between 2020 and 2025 has finally overwhelmed its capacity. In response, NIST has fundamentally abandoned its “analyze everything” mission, pivoting to a risk‑based model that enriches only vulnerabilities listed in CISA’s Known Exploited Vulnerabilities (KEV) catalog, those affecting federal systems, or those classified as critical software.
Learning Objectives:
- Understand the scope and impact of NIST’s policy shift on global vulnerability management.
- Learn to operationalize alternative prioritization frameworks (KEV, EPSS, LEV) using practical Linux/Windows commands and APIs.
- Implement automated, risk‑based patch management strategies to compensate for gaps in NVD enrichment.
You Should Know:
- The New NVD Prioritization Matrix – What Gets Enriched and What Dies in the Backlog
Starting April 15, 2026, NIST will only enrich CVEs that satisfy at least one of three conditions: presence in the CISA KEV catalog, software used by the U.S. federal government, or critical software as defined by Executive Order 14028 (e.g., operating systems, identity/access management systems, network protection tools). All other CVEs—including the more than 30,000 already languishing in backlog—will be marked “Not Scheduled” and will never receive NIST‑provided severity scores or configuration data. Users can request enrichment for a specific CVE by emailing [email protected], but there is no guarantee of processing.
Step‑by‑step guide – Programmatically identifying high‑priority CVEs using the CISA KEV API:
Many security teams rely on the NVD as a primary data source, but with the new “Not Scheduled” status, you must shift to alternative sources. The CISA KEV catalog provides a curated list of vulnerabilities with confirmed in‑the‑wild exploitation—exactly the set NIST will now prioritize. Use the following bash script to fetch the entire KEV catalog and extract only the CVEs, then compare them against your local asset inventory.
Download the official CISA KEV catalog (JSON format) curl -s https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json -o kev.json Extract just the CVE IDs from the catalog jq -r '.vulnerabilities[].cveID' kev.json > kev_cves.txt Count how many KEV entries you have echo "Total KEV CVEs: $(wc -l < kev_cves.txt)" (Optional) Compare against a list of CVEs affecting your environment (e.g., from a scanner) Assuming you have a file 'my_cves.txt' with one CVE per line: grep -F -f my_cves.txt kev_cves.txt > critical_patch_list.txt echo "CVEs from your environment that are actively exploited: $(wc -l < critical_patch_list.txt)"
Windows PowerShell alternative:
Download KEV catalog using PowerShell
Invoke-WebRequest -Uri "https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json" -OutFile "kev.json"
Parse JSON and extract CVE IDs
$kev = Get-Content -Raw -Path "kev.json" | ConvertFrom-Json
$kev.vulnerabilities.cveID | Out-File -FilePath "kev_cves.txt"
Compare with your asset list (assuming my_cves.txt exists)
$myCves = Get-Content "my_cves.txt"
$kevCves = Get-Content "kev_cves.txt"
$critical = $myCves | Where-Object { $_ -in $kevCves }
$critical | Out-File -FilePath "critical_patch_list.txt"
Write-Host "Active exploited CVEs in your environment: $($critical.Count)"
- Abandoning CVSS for EPSS – Why Static Severity Scores Are Dead
NIST will no longer routinely provide a separate severity score for CVEs that already have a score from their CVE Numbering Authority (CNA). This means the already‑limited value of CVSS (which measures theoretical impact, not real‑world exploitability) becomes even less reliable. Modern security teams must adopt probability‑driven models such as the Exploit Prediction Scoring System (EPSS), which uses machine learning to predict the likelihood that a vulnerability will be exploited within 30 days. EPSS scores range from 0 to 100% and are updated daily based on live threat intelligence.
Step‑by‑step guide – Querying EPSS scores for your CVEs and integrating them into patch prioritization:
EPSS provides a free API that returns the probability of exploitation for any CVE. Use this script to enrich your vulnerability list with EPSS scores and sort by risk.
Define a function to query EPSS API for a single CVE
get_epss() {
local cve=$1
curl -s "https://api.first.org/data/v1/epss?cve=${cve}" | jq -r '.data[bash] | "(.cve): EPSS=(.epss) (percentile=(.percentile))"'
}
Loop through your CVE list (e.g., from kev_cves.txt or my_cves.txt)
while read cve; do
get_epss "$cve"
done < kev_cves.txt > epss_scores.txt
Sort by EPSS score (highest first)
sort -t'=' -k2 -nr epss_scores.txt
For a more comprehensive approach, use the open‑source `epss_tool` (Python) to fetch scores for thousands of CVEs at once:
Install EPSS Python client pip install epss Fetch scores for all KEV CVEs epss --file kev_cves.txt --output epss_results.csv
Windows (using Python): Same commands work in PowerShell if Python is installed. Alternatively, use `Invoke-RestMethod` to call the EPSS API directly.
- Implementing LEV (Likely Exploited Vulnerabilities) for Strategic Risk Planning
NIST itself has acknowledged that CVSS is inadequate and has proposed its own metric called LEV (Likely Exploited Vulnerabilities), a statistical model that estimates the probability (0‑1) of exploitation within a defined window (e.g., 90 days). LEV integrates multiple data sources: CVSS vector strings, public proof‑of‑concept (PoC) availability, KEV inclusion, patch adoption rates, and historical exploit frequency. Although NIST has not yet operationalized LEV via a public API, security teams can approximate its logic using open data.
Step‑by‑step guide – Building a simple LEV‑like prioritization score using available signals:
import requests
import json
def calculate_lev_score(cve_id):
score = 0.0
Signal 1: KEV inclusion (highest weight)
kev_list = requests.get("https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json").json()
if any(cve_id == vuln['cveID'] for vuln in kev_list['vulnerabilities']):
score += 0.6
Signal 2: EPSS probability (scale 0-1)
epss_resp = requests.get(f"https://api.first.org/data/v1/epss?cve={cve_id}").json()
if epss_resp['data']:
score += float(epss_resp['data'][bash]['epss']) 0.3
Signal 3: Public PoC existence (simplified: check Exploit-DB)
In production, use a proper threat intelligence feed
edb_search = requests.get(f"https://exploit-db.com/search?cve={cve_id}")
if "exploit" in edb_search.text.lower():
score += 0.1
return min(score, 1.0)
Example usage
cve = "CVE-2025-60710"
lev = calculate_lev_score(cve)
print(f"LEV score for {cve}: {lev:.2f} (higher = more likely exploited)")
- Automating Patch Deployment Based on Risk Scores (Linux & Windows)
Once you have prioritized CVEs using KEV, EPSS, or LEV, you must automate remediation to meet required timelines. CISA’s Binding Operational Directive (BOD) 22‑01 mandates that federal agencies patch KEV vulnerabilities within specific deadlines (typically 2 weeks for critical flaws). Even for non‑federal organizations, adopting a similar SLA is a best practice.
Step‑by‑step guide – Linux (Debian/Ubuntu) automated patching for critical CVEs:
!/bin/bash
critical_patch.sh – Install only security updates related to KEV CVEs
Requires a list of KEV CVEs in kev_cves.txt
Update package database
sudo apt update
Get list of installed packages with known vulnerabilities
This example uses `apt-get changelog` to grep for CVE IDs; in production use a proper scanner like Vulners or Grype
for pkg in $(dpkg -l | grep ^ii | awk '{print $2}'); do
changelog=$(apt-get changelog $pkg 2>/dev/null)
for cve in $(cat kev_cves.txt); do
if echo "$changelog" | grep -qi "$cve"; then
echo "Package $pkg has fix for $cve – applying update"
sudo apt install --only-upgrade -y $pkg
fi
done
done
Windows PowerShell automated patching (using Windows Update and WSUS):
critical_patch.ps1 – Install updates that address specific CVEs
Requires KB numbers or direct CVE-to-update mapping (use a third‑party feed like VulnCheck)
$kevCves = Get-Content "kev_cves.txt"
Get available updates from Windows Update
$updates = Get-WUList -MicrosoftUpdate
foreach ($update in $updates) {
$cvesInUpdate = $update.CveIDs
if ($cvesInUpdate | Where-Object { $_ -in $kevCves }) {
Write-Host "Installing $($update.) – addresses KEV CVEs"
Install-WUUpdate -Update $update -AcceptAll -AutoReboot:$false
}
}
5. Hardening Cloud Environments Against “Not Scheduled” Vulnerabilities
Because NIST will no longer enrich the vast majority of CVEs, cloud workloads become particularly vulnerable to unknown or underestimated risks. Attackers often target misconfigured containers, serverless functions, and exposed APIs that may correspond to unenriched CVEs. You must shift from reactive patching to proactive defense in depth.
Step‑by‑step guide – Using open‑source tools to detect and mitigate unenriched CVEs in Kubernetes:
Install Grype (vulnerability scanner for containers)
curl -sSfL https://raw.githubusercontent.com/anchore/grype/main/install.sh | sh -s -- -b /usr/local/bin
Scan a container image for all CVEs (including those not enriched by NIST)
grype myapp:latest -o json > grype_report.json
Filter for CVEs that are NOT in the KEV catalog (but may still be risky)
jq -r '.matches[].vulnerability.id' grype_report.json | grep -v -F -f kev_cves.txt > non_kev_cves.txt
For each non‑KEV CVE, fetch EPSS score and patch if EPSS > 0.1 (10% exploit probability)
while read cve; do
epss=$(curl -s "https://api.first.org/data/v1/epss?cve=${cve}" | jq -r '.data[bash].epss // 0')
if (( $(echo "$epss > 0.1" | bc -l) )); then
echo "High EPSS score for non‑KEV CVE $cve – patching required"
Trigger rebuild of image or apply admission control
fi
done < non_kev_cves.txt
API Security – Hardening against unenriched API vulnerabilities:
Many API vulnerabilities never make it into the NVD, or if they do, they are marked “Not Scheduled.” Implement a Web Application Firewall (WAF) rule to block known attack patterns regardless of CVE status.
Example ModSecurity rule to block SQL injection and path traversal (generic) Save as /etc/modsecurity/custom_rules.conf SecRule ARGS "@detectSQLi" "id:1001,phase:2,deny,status:403,msg:'Generic SQL injection blocked'" SecRule REQUEST_URI "@detectPathTraversal" "id:1002,phase:1,deny,status:403,msg:'Path traversal blocked'"
6. What Undercode Says
- NVD is no longer a source of truth. The backlog of unenriched CVEs means you cannot rely on NIST for timely or complete vulnerability data. You must adopt multiple independent feeds (KEV, EPSS, vendor bulletins) and automate prioritization.
- Probability over severity. CVSS is dead for prioritization; EPSS and LEV provide real‑world exploitability predictions that reduce alert fatigue and focus resources on vulnerabilities that actually get exploited.
- Shift‑left and defense‑in‑depth are mandatory. When a vulnerability is “Not Scheduled,” assume it will be weaponized. Implement generic exploit blocking at the WAF, runtime application self‑protection (RASP), and network segmentation to mitigate unknown risks.
7. Prediction: The Fragmentation of Vulnerability Intelligence
NIST’s retreat from comprehensive enrichment will accelerate the fragmentation of vulnerability intelligence. Private vendors (e.g., VulnCheck, Aikido, Snyk) will become the de facto sources for enriched CVE data, creating a tiered market where only well‑funded organizations can afford complete visibility. This will widen the security gap between large enterprises and smaller entities, leading to a rise in attacks targeting the “long tail” of unenriched vulnerabilities. Expect regulatory pressure on CISA to expand the KEV catalog dramatically, as well as increased adoption of machine‑learning‑based vulnerability discovery tools that bypass the NVD entirely.
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Reported By: Hackermohitkumar Nist – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
