fix(security): harden template rendering #319

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opened 2026-02-22 23:41:15 +00:00 by freemo · 1 comment
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Metadata

  • Commit Message: fix(security): harden template rendering
  • Branch: feature/m4-security-template

Background

Unsafe template usage is replaced with a sandboxed renderer using a strict token set. Attribute access, function calls, and filters are denied — only {var} substitution from a fixed allowlist is permitted. Max template length and max render output size checks enforce limits.

Acceptance Criteria

  • Replace unsafe template usage with a sandboxed renderer and strict token set.
  • Deny attribute access, function calls, and filters; allow only {var} substitution with a fixed allowlist.
  • Add max template length + max render output size checks with explicit errors.
  • Add template allowlist validation for each template context key and log rejected keys.
  • Add unit helper to pre-validate template strings at action/plan creation time.

Definition of Done

This issue is complete when:

  • All subtasks below are completed and checked off.
  • A Git commit is created where the first line of the commit message matches
    the Commit Message in Metadata exactly, followed by a blank line, then
    additional lines providing relevant details about the implementation. The
    commit body should be appropriate in size for a commit message and relatively
    complete in describing what was done.
  • The commit is pushed to the remote on the branch matching the Branch in
    Metadata exactly.
  • The commit is submitted as a pull request to master, reviewed, and
    merged before this issue is marked done.

Subtasks

  • Replace unsafe template usage with a sandboxed renderer and strict token set.
  • Deny attribute access, function calls, and filters; allow only {var} substitution with a fixed allowlist.
  • Add max template length + max render output size checks with explicit errors.
  • Add template allowlist validation for each template context key and log rejected keys.
  • Add unit helper to pre-validate template strings at action/plan creation time.
  • Add docs/reference/template_security.md with safe patterns.
  • Tests (Behave): Add features/security_templates.feature scenarios.
  • Tests (Robot): Add robot/security_templates.robot smoke tests.
  • Tests (ASV): Add benchmarks/security_template_bench.py for render baseline.
  • Verify coverage >=97% via nox -s coverage_report. If coverage is <97% then review the current unit test coverage report at build/coverage.xml and use it to write new Behave based unit tests to improve code coverage. Specifically, write Behave style unit tests that are descriptively named and specifically improves coverage on whichever file has the most uncovered lines by writing tests that will target the uncovered lines in the report. Once that is done rerun nox -s coverage_report to verify all tests pass and coverage is above >=97%. Only mark this as complete once coverage is >=97%, if not repeat this task as many times as is needed until coverage reaches >=97%.
  • Run nox (all default sessions, including benchmark), fix any errors if needed ensuring nox passes across entire code base, do not ignore any failure even if it seems unrelated to this commit, fix it.

Section: ### Section 11: Security & Safety [WORKSTREAM F - Luis + Brent]
Status: Open

## Metadata - **Commit Message**: `fix(security): harden template rendering` - **Branch**: `feature/m4-security-template` ## Background Unsafe template usage is replaced with a sandboxed renderer using a strict token set. Attribute access, function calls, and filters are denied — only `{var}` substitution from a fixed allowlist is permitted. Max template length and max render output size checks enforce limits. ## Acceptance Criteria - [ ] Replace unsafe template usage with a sandboxed renderer and strict token set. - [ ] Deny attribute access, function calls, and filters; allow only `{var}` substitution with a fixed allowlist. - [ ] Add max template length + max render output size checks with explicit errors. - [ ] Add template allowlist validation for each template context key and log rejected keys. - [ ] Add unit helper to pre-validate template strings at action/plan creation time. ## Definition of Done This issue is complete when: - All subtasks below are completed and checked off. - A Git commit is created where the **first line** of the commit message matches the Commit Message in Metadata exactly, followed by a blank line, then additional lines providing relevant details about the implementation. The commit body should be appropriate in size for a commit message and relatively complete in describing what was done. - The commit is pushed to the remote on the branch matching the **Branch** in Metadata exactly. - The commit is submitted as a **pull request** to `master`, reviewed, and **merged** before this issue is marked done. ## Subtasks - [ ] Replace unsafe template usage with a sandboxed renderer and strict token set. - [ ] Deny attribute access, function calls, and filters; allow only `{var}` substitution with a fixed allowlist. - [ ] Add max template length + max render output size checks with explicit errors. - [ ] Add template allowlist validation for each template context key and log rejected keys. - [ ] Add unit helper to pre-validate template strings at action/plan creation time. - [ ] Add `docs/reference/template_security.md` with safe patterns. - [ ] Tests (Behave): Add `features/security_templates.feature` scenarios. - [ ] Tests (Robot): Add `robot/security_templates.robot` smoke tests. - [ ] Tests (ASV): Add `benchmarks/security_template_bench.py` for render baseline. - [ ] Verify coverage >=97% via `nox -s coverage_report`. If coverage is <97% then review the current unit test coverage report at `build/coverage.xml` and use it to write new Behave based unit tests to improve code coverage. Specifically, write Behave style unit tests that are descriptively named and specifically improves coverage on whichever file has the most uncovered lines by writing tests that will target the uncovered lines in the report. Once that is done rerun `nox -s coverage_report` to verify all tests pass and coverage is above >=97%. Only mark this as complete once coverage is >=97%, if not repeat this task as many times as is needed until coverage reaches >=97%. - [ ] Run `nox` (all default sessions, including benchmark), fix any errors if needed ensuring nox passes across **entire** code base, do not ignore any failure even if it seems unrelated to this commit, fix it. **Section**: ### Section 11: Security & Safety [WORKSTREAM F - Luis + Brent] **Status**: Open
freemo added this to the (deleted) milestone 2026-02-22 23:41:15 +00:00
freemo modified the milestone from (deleted) to v3.3.0 2026-02-23 00:07:07 +00:00
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Owner

Expected completion updated (Day 15 rebaseline): Day 35 / 2026-03-15 (previously Day 26 / 2026-03-06)

**Expected completion updated (Day 15 rebaseline):** Day 35 / 2026-03-15 (previously Day 26 / 2026-03-06)
freemo added the due date 2026-02-19 2026-02-23 18:41:51 +00:00
CoreRasurae added reference develop-luis-2 2026-02-25 07:40:31 +00:00
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2026-02-19

Reference
cleveragents/cleveragents-core#319
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