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FortiOS version numbering: branches, patch releases and the Feature and Mature labels

How a FortiOS version is numbered, what a branch is, what Fortinet means by a Feature release and a Mature release, how the recommended release per model differs from both, and where each fact is published.

Who it is for
Engineers who run FortiGate firewalls and read FortiOS version numbers in advisories, release notes and inventories.
Scope
FortiOS on FortiGate (hardware and virtual). FortiManager, FortiAnalyzer and the other Fortinet products share the numbering but have their own branches, labels and life cycles.

Published 19 Oct 2026 · Updated 19 Oct 2026 · Sources checked 19 Oct 2026

What a FortiOS version number says

A FortiOS version has three numbers. The first two name the branch, which Fortinet documents as a release train with its own release notes, its own life cycle dates and its own set of supported models. The third number counts the patch releases of the branch: each one fixes issues and may add minor features, and the release notes of each state what it resolves, what remains known and which models it supports.

Branches live side by side for years. A vulnerability is fixed in each supported branch by its own patch release, which is why FortiGuard advisories state the affected and fixed releases per branch (“upgrade to this release or above” on one branch, another release on the next). The number alone does not tell whether a release fixes a vulnerability, whether it supports a model or whether Fortinet recommends it.

WrittenWhat it isWhere Fortinet documents it
7.6A branch (release train)The branch's page in the Document Library; its dates in the Product Life Cycle
7.6.4The fourth patch release of the 7.6 branchIts release notes: supported models, resolved issues, known issues, upgrade information
7.6.4 (M)The same release, labelled Mature in Fortinet's release informationThe branch's release information and the release notes
The form of the identifiers; the numbers are an example, not the current releases. A dated example written for this guide; the current releases are in the live block and on the product pages.

Feature and Mature releases

Fortinet labels the releases of a branch. The first releases of a branch are Feature releases: they carry the new capabilities the branch introduces and the changes that come with them. Later releases of the branch are labelled Mature: Fortinet publishes them with stability and fixes as their purpose, after the branch has been deployed widely. The label is stated in the branch's release information and repeated in the release notes.

Mature is a statement about the release's purpose and age in the branch. It is not, by itself, the vendor's recommendation for your appliance: Fortinet's recommended release is published per model, and a Mature release may be older than the first fixed release of an advisory that concerns you. Read the three statements apart.

The recommended release per model

Fortinet publishes, in a technical tip maintained by its staff, the recommended FortiOS release for each FortiGate model and series. The recommendation names one release per model, sometimes different releases for models of the same branch, and is revised as branches mature. Patcharo reads that statement about every six hours and shows it per model on the product pages, with the day it was last verified: the live block below carries the current statement for the branches still supported.

A recommended release answers “which release does Fortinet advise for this model today?”. It does not answer “does this release fix the vulnerability that concerns me?”: that answer is in the PSIRT advisory, per branch, and may name a release above the recommended one.

End of engineering support and end of support

Each branch has two dates in Fortinet's Product Life Cycle. After the end of engineering support, the branch no longer receives regular patch releases; after the end of support, it receives nothing and the vendor's support for it ends. An advisory therefore states fixed releases for the branches still in engineering support, and a device on an older branch has no fixed release in its branch: the fix is a branch change.

  • To know what a release fixes and keeps, read its release notes: Resolved Issues and Known Issues, with Fortinet's bug identifiers.
  • To know whether a release exists for your model, read the release notes' supported models and the branch's release information.
  • To know what Fortinet advises for your model, read the recommended release technical tip.
  • To know whether a release fixes a vulnerability, read the FortiGuard advisory: it states the fixed release of each branch.
  • To know how long a branch is maintained, read the Product Life Cycle.

The current FortiOS releases, as the catalog reads them

Patcharo reads the Document Library page of each supported branch about every six hours and lists every release it names, with the release date its notes state; the recommended release per model comes from Fortinet's technical tip. The block below is that reading, verified and dated.

Current versions, from the catalog

Read from the vendor's own documents by the collection described in this guide; the examples in the text are illustrative and dated, these facts are live.

FortiOS

Product page
  • 8.0Latest public release —Vendor recommendation —Not collected
  • 7.6Latest public release —Vendor recommendation 7.6.6Not collected
  • 7.4Latest public release —Vendor recommendation 7.4.11Not collected

Availability, recommendation and support are read from the vendor's documents and shown apart; a release Patcharo lists is not advice to install it.

Frequent mistakes

  • Reading Mature as “recommended for my appliance”: the recommendation is per model and may name another release.
  • Reading a fixed release stated for one branch as valid for another branch.
  • Choosing the newest patch release without reading its supported models and its known issues.
  • Staying on a branch past its end of engineering support and expecting a fixed release in it.

What to verify before acting

  • The exact release the appliance reports and its model.
  • The fixed release the advisory states for your branch.
  • The recommended release for your model in Fortinet's technical tip, and its date.
  • The supported models of the release you consider, and the dates of your branch in the Product Life Cycle.

Sources

The official documents this guide rests on, read against the text on 19 Oct 2026. Nothing here is copied from them: read them for the authoritative wording.