[WIP] Fix Black arbitrary file writes vulnerability

[Claude]

Thanks for assigning this alert to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

---

This section details the Dependabot vulnerability alert you should resolve

<alert_title>Black: Arbitrary file writes from unsanitized user input in cache file name</alert_title>
<alert_description>### Impact

Black writes a cache file, the name of which is computed from various formatting options. The value of the --python-cell-magics option was placed in the filename without sanitization, which allowed an attacker who controls the value of this argument to write cache files to arbitrary file system locations.

Patches

Fixed in Black 26.3.1.

Workarounds

Do not allow untrusted user input into the value of the --python-cell-magics option.</alert_description>

high
GHSA-3936-cmfr-pm3m, CVE-2026-32274
black
pip
<vulnerable_versions>< 26</vulnerable_versions>
<patched_version>26.3.1</patched_version>
<manifest_path>requirements/testing/all.txt</manifest_path>

https://github.com/psf/black/security/advisories/GHSA-3936-cmfr-pm3m https://github.com/psf/black/pull/5038 https://github.com/psf/black/commit/4937fe6cf241139ddbfc16b0bdbb5b422798909d https://github.com/psf/black/releases/tag/26.3.1 https://nvd.nist.gov/vuln/detail/CVE-2026-32274 https://github.com/advisories/GHSA-3936-cmfr-pm3m

<task_instructions>Resolve this alert by updating the affected package to a non-vulnerable version. Prefer the lowest non-vulnerable version (see the patched_version field above) over the latest to minimize breaking changes. Include a Reachability Assessment section in the PR description. Review the alert_description field to understand which APIs, features, or configurations are affected, then search the codebase for usage of those specific items. If the vulnerable code path is reachable, explain how (which files, APIs, or call sites use the affected functionality) and note that the codebase is actively exposed to this vulnerability. If the vulnerable code path is not reachable, explain why (e.g. the affected API is never called, the vulnerable configuration is not used) and note that the update is primarily to satisfy vulnerability scanners rather than to address an active risk. If the advisory is too vague to determine reachability (e.g. 'improper input validation' with no specific API named), state that reachability could not be determined and explain why. Include a confidence level in the reachability assessment (e.g. high confidence if the advisory names a specific API and you confirmed it is or is not called, low confidence if the usage is indirect and hard to trace). If no patched version is available, check the alert_description field for a Workarounds section — the advisory may describe configuration changes or usage patterns that mitigate the vulnerability without a version update. If a workaround is available, apply it and leave a code comment referencing the advisory identifier explaining it is a temporary mitigation. If neither a patch nor a workaround is available, explain in the PR description why the alert cannot be resolved automatically so a human reviewer can take over. Inspect the repository to determine which package manager is used (e.g. lock files, config files, build scripts) and use that tooling to perform the update — do not edit lock files directly. If the version constraint in the manifest (e.g. package.json, Gemfile, pyproject.toml) caps the version below the fix, update the constraint first. For transitive dependencies, determine whether it is simpler to update the direct dependency that pulls in the vulnerable package or to update the transitive dependency directly, and choose the least disruptive approach. If upgrading to fix the vulnerability forces a major version bump or known breaking changes, review the changelog or release notes, then audit the codebase for usage of affected APIs and fix any breaking changes that are found. If the package manager fails to resolve dependencies (e.g. peer dependency conflicts, incompatible engine constraints), document the error in the PR description rather than attempting increasingly complex workarounds. After updating, check the lock file to confirm the package no longer resolves to a version in the vulnerable range. Keep changes minimal and tightly scoped. Ensure tests, build, type checking, and linting all pass after your changes. If there are any test, lint, or typechecking failures, investigate whether they are caused by the update and fix them if so — do not leave broken tests in the PR. If they were already present before the update, note them in the PR description so a human reviewer can assess whether they are related.</task_instructions>

• Resolves MLXPorts/mlx-matplotlib alert Bump pillow from 10.3.0 to 12.1.1 in /requirements/testing #10