GitHub Actions Blocks pull_request_target by Default: Deadline Pushed to December 2

On November 2, 2026, GitHub announced it is pushing back to December 2 the default
blocking of workflows triggered by pull_request_target on public repositories.
The deadline, originally set a month earlier, gives teams more time to audit their pipelines
before the platform cuts off by default a trigger regularly tied to leaked secrets. The change
applies to the GitHub Free, Team and Enterprise Cloud plans, and is part of a wider set of
governance changes GitHub has rolled out this autumn.

#What changes on December 2

Starting December 2, 2026, GitHub Actions will block pull_request_target
events by default on every public repository, unless an Actions event policy explicitly
allows them. Private and internal repositories are not affected by this switch, nor are
GitHub Enterprise Server instances.

#Why this trigger worries GitHub

Unlike pull_request, the pull_request_target trigger runs the
workflow in the context of the base repository rather than the contributor’s fork.

This trigger runs in the context of the base repository and can access its secrets.

A poorly built workflow that checks out and executes fork code without care exposes the
base repository’s tokens and secrets to untrusted code. This is the exact pattern, documented
for years in CI/CD security reports, that GitHub is targeting with this default block.

#Who is affected, and who isn’t

#Transition timeline

During the two brownout windows, affected runs fail with an explicit error annotation,
making it possible to pinpoint exactly which workflows need fixing before the final deadline.

#How to respond before the deadline

Teams that legitimately rely on pull_request_target, for instance to post a
comment on a pull request from a fork without ever executing its code, can explicitly allow it
through an Actions event policy targeting the relevant workflow files — in the same spirit as
the recent fine-tuning of CI cache access:

name: comment-on-fork-pr
on:
  pull_request_target:
    types: [opened, synchronize]

permissions:
  pull-requests: write

jobs:
  comment:
    runs-on: ubuntu-latest
    steps:
      # No checkout of the fork's code: only the API is used.
      - name: Post a comment
        uses: actions/github-script@v7
        with:
          script: |
            github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.payload.pull_request.number,
              body: "Thanks for this contribution."
            })

#Key takeaways

The default blocking of pull_request_target on public repositories has been
pushed back a month, to December 2, 2026. Open source maintainers have until November 9 to
audit their workflows via Insights, then until November 16 to watch the two test windows
before the final switch. An Actions event policy lets legitimate uses of the trigger continue
without reintroducing the risk of leaked secrets.

Further reading: the full announcement on the
GitHub changelog.