bcquality/microsoft/knowledge/security/do-not-expose-sensitive-data-in-event-publishers.md
Jesper Schulz-Wedde 0540c7bf6e Reframe seed-article banners as community contribution invitations
The 35 articles still in their seed form previously carried a banner
reading "Seed article. ... Domain stewards should expand, restructure,
and refine as needed." For a community preview, that phrasing reads as
"TODO left in production" to first-time visitors.

Replace all three banner variants (performance-seeded, security-seeded,
community-ported) with a single positive invitation:

> Contributions welcome — open a PR to refine or extend this article.

Content and structure of the articles are unchanged; only the leading
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2026-04-23 17:31:36 +02:00

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bc-version domain keywords technologies countries application-area
all
security
event
publisher
extensibility
var-parameter
al
w1
all

Do not expose sensitive data in event publishers

Contributions welcome — open a PR to refine or extend this article.

Description

Events in AL are extensibility contracts. Every subscriber — third-party, internal, or installed after the fact — receives the full set of event parameters. Parameters that carry secrets, pre-authorization state, or variables the publisher relies on for access control effectively become public, and var-parameters can be mutated by a subscriber to alter publisher behaviour.

Best Practice

Design event signatures to carry only the data a subscriber legitimately needs. Do not pass SecretText, credential material, or flags the publisher depends on for access control. If a subscriber needs to veto an action, model it as a separate OnBefore event whose Handled pattern is documented — not as a general-purpose var Boolean callers can flip.

See sample: do-not-expose-sensitive-data-in-event-publishers.good.al.

Anti Pattern

An OnBeforeElevateAccess publisher that exposes var CanAccess: Boolean — any subscriber installed on the tenant can flip it to true and escalate. Or a publisher that passes a SecretText parameter it obtained internally, handing it to every subscriber.

See sample: do-not-expose-sensitive-data-in-event-publishers.bad.al.