Debian

Debian is a community-developed distribution that publishes a new stable release about every two years. Each release gets around three years of regular security support from the Debian Security Team, followed by two years of Long Term Support (LTS) from the Debian LTS team. After that, Freexian offers Extended LTS (ELTS) commercially, for a subset of packages.

How security updates work on Debian

The Debian Security Team handles security for the current stable release. Instead of moving packages to new upstream versions, it backports the fix to the version already in the release. Each fix is announced as a Debian Security Advisory (DSA) and published to Debian's security archive. Once a release moves to LTS, the Debian LTS team takes over and publishes Debian LTS Advisories (DLA) instead.

Every known vulnerability is recorded in the Debian Security Tracker, with its urgency and the version that fixes it. Minor issues that don't warrant an advisory are often fixed in the next point release instead.

How OS Checker tracks Debian

OS Checker compares each machine's installed packages against Debian's main archive and security archive. For every outdated package, the Debian Security Tracker tells whether the available version fixes a known CVE, which makes it vulnerable rather than just outdated. Fixes published only through Freexian's ELTS repository aren't tracked.

See the full list of supported releases.