diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 653bdb1b4..89a5e632b 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -9563,6 +9563,20 @@ system and gives an overview of their function and contents.
       increases the SBOM size (potentially by several gigabytes for typical
       images).
 
+   :term:`SPDX_INCLUDE_VEX`
+      This option controls what `VEX <https://cyclonedx.org/capabilities/vex/>`__
+      information will be present in the output SPDX documents.
+
+      It can take three different values:
+
+      -  ``none``: disable all VEX data.
+
+      -  ``current`` (default): include VEX data for vulnerabilities not already
+         fixed in the upstream source code.
+
+      -  ``all``: get all known historical vulnerabilities, including those
+         already fixed upstream (warning: this can be large and slow).
+
    :term:`SPDX_INVOKED_BY`
       The base variable name describing the agent that invoked the build.
       Each ``Build`` object in the SPDX output is linked to this agent with an