Get zero-day alerts from four kinds of source: vendor security advisories for products you run, the CISA Known Exploited Vulnerabilities catalog for confirmed exploitation, open source advisory databases for libraries, and automated matching against your own inventory. No single feed is enough, and social media is a lead, not a source.
The four source types
| Source | Strength | Weakness |
|---|---|---|
| Vendor advisories | Authoritative on fixes and workarounds | You must subscribe to each vendor |
| CISA KEV catalog | Confirms exploitation in the wild | Lists only entries CISA has added, so it can trail first attacks |
| Open source advisory databases | Package and version data for libraries | Quality varies, some entries unreviewed |
| Matching against your inventory | Tells you if it matters to you | Only as good as the inventory |
The KEV catalog in practice
CISA states that organizations should use the KEV catalog as an input to their vulnerability management prioritization framework, and describes it as the authoritative source of vulnerabilities exploited in the wild. Each entry carries the CVE, the vendor and product, and a due date. For more background, see what the KEV catalog is.
Treat a KEV entry for a product you run as a trigger for your response process, not as an item for next month's backlog.
Open source advisories
The GitHub Advisory Database lists vulnerabilities and malware in open source packages across ecosystems including npm, Maven, pip, Go, NuGet, RubyGems and Rust. GitHub marks advisories as reviewed or unreviewed. Reviewed ones are checked for validity and completeness; unreviewed ones come automatically from the National Vulnerability Database feed and do not trigger Dependabot alerts. Know which kind you are reading.
Build a small subscription list
Do not subscribe to everything. List your top vendors by exposure, such as the firewall, identity provider, hypervisor, file transfer tool and the main language runtimes. Subscribe to those advisory feeds, route them to one channel, and review that channel daily.
Alerts need an owner
An alert nobody triages is noise. Assign a rotating person to read the channel each day and open an incident when a KEV entry or a vendor advisory matches your inventory.
Where Safeguard fits
Safeguard's zero-day discovery work compares new advisories to your dependency inventory so the match step is automatic. A free scan shows the inventory it works from.
Try it yourself
Click through it at your own pace, or open it full screen.
Watch how a new advisory is matched to projects that use the affected package.
Quick check
Is the KEV catalog a zero-day feed?
It lists vulnerabilities confirmed as exploited. Some were zero-days, many are older. Use it to confirm real attacks, not as an early warning system.
Should we follow security news on social media?
Use it as a lead, then confirm in a primary source before acting.
Sources
Last reviewed: 19 October 2026.
