Update cryptography requirement from >=48.0.1 to >=50.0.0 in /backend

[dependabot]

Updates the requirements on cryptography to permit the latest version.

Changelog

Sourced from cryptography's changelog.

50.0.0 - 2026-07-31

* **SECURITY ISSUE**:
  :func:`~cryptography.hazmat.primitives.serialization.pkcs7.pkcs7_decrypt_der`
  and its PEM and S/MIME variants no longer expose distinguishable errors or
  timing when unwrapping a ``RecipientInfo``'s ``encryptedKey``, which could
  act as a Bleichenbacher oracle for callers that decrypt untrusted messages.
  A random key is now substituted on failure, as described in :rfc:`3218`.
  Credit to **@X1AOxiang** for reporting the issue. **CVE-2026-69247**
* Deprecated Diffie-Hellman key exchange over finite fields (FFDH).
  Everything FFDH is deprecated, including the types in
  ``cryptography.hazmat.primitives.asymmetric.dh`` and loading FFDH keys or
  parameters with the key loading APIs. Users should migrate to a more
  modern key exchange algorithm.
* Added ``xof()`` class methods to
  :class:`~cryptography.hazmat.primitives.hashes.SHAKE128` and
  :class:`~cryptography.hazmat.primitives.hashes.SHAKE256` for constructing
  algorithm instances configured for use with
  :class:`~cryptography.hazmat.primitives.hashes.XOFHash`.
* The :mod:`X.509 verification <cryptography.x509.verification>` APIs are now
  considered stable and are subject to our API stability policy.
* Added the :doc:`/cobblestone` recipe, an implementation of the
  Cobblestone-128 and Cobblestone-256 instantiations of the `C2SP
  chunked-encryption specification
  <https://c2sp.org/chunked-encryption>`_ for streaming authenticated
  encryption of large messages.
* Parsing a Signed Certificate Timestamp list now rejects encodings that
  carry trailing bytes after the list or after an individual SCT, instead of
  silently ignoring them.
* Added support for using :class:`~cryptography.x509.Name` as a field type in
  the :doc:`/hazmat/asn1/index` module.
* Loading a public key or an EC private key now rejects DER where the
  ``subjectPublicKey`` (or EC ``publicKey``) ``BIT STRING`` declares a non-zero
  number of unused bits, instead of silently ignoring it.
* Parsing a CRL entry's ``InvalidityDate`` extension now rejects a
  ``GeneralizedTime`` that carries fractional seconds or another non-DER form,
  matching the strict encoding already required for every other X.509 time
  field.
* :func:`~cryptography.x509.ocsp.load_der_ocsp_request` and
  :func:`~cryptography.x509.ocsp.load_der_ocsp_response` now reject a request
  or response whose ``version`` field is not ``v1``, the only version defined
  by RFC 6960, matching the version validation already performed when loading
  certificates, CSRs and CRLs.
* :class:`~cryptography.hazmat.primitives.hashes.XOFHash` is now supported
  when building against AWS-LC.
* HMAC (and therefore PBKDF2-HMAC) with SHA-3 hashes is now supported when
  building against AWS-LC.
* Diffie-Hellman (:doc:`/hazmat/primitives/asymmetric/dh`) is now supported
  when building against AWS-LC.
</tr></table> 

... (truncated)

Commits

• dcb7050 Prepare for 50.0.0 release (#15372)
• 53fccd9 Don't leak how PKCS#7 encryptedKey decryption failed (#15369)
• d472f97 Add from __future__ import annotations to all src/ Python files (#15371)
• 908773d Bump downstream dependencies in CI (#15368)
• 2cc07cc Bump BoringSSL, OpenSSL, AWS-LC in CI (#15367)
• c94ede9 chore(deps): bump ruff from 0.16.0 to 0.16.1 (#15366)
• 67a8308 chore(deps): bump virtualenv from 21.7.0 to 21.7.1 (#15365)
• 95018ff Release the GIL in one-shot AEAD encrypt/decrypt (#15361)
• 6954733 Release the GIL during DH and DSA parameter generation (#15364)
• 6893b94 Import _serialization instead of serialization in x509/extensions (#15363)
• Additional commits viewable in compare view

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[vercel]

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Project	Deployment	Actions	Updated (UTC)
pycon	Ready	Preview	Aug 27, 2026 3:19pm

[marcoacierno]

@claude update the lock file

Remember you can rely on CI to run the full test suite

In your recap, assert how safe this upgrade is

[claude]

Claude finished @marcoacierno's task in 3m 19s —— View job

---

Lock file updated ✅

• Gather context (read PR diff + backend/pyproject.toml)
• Check current cryptography pin in backend/uv.lock
• Run uv lock to regenerate the lock file
• Audit repo usage of cryptography against 50.0.0 breaking changes
• Run backend checks (mypy / ruff / relevant tests)
• Commit & push (459cc67)
• Recap with a safety assessment

---

What changed

uv lock resolved cleanly — cryptography 48.0.1 → 50.0.1, and nothing else moved:

Resolved 236 packages in 916ms
Updated cryptography v48.0.1 -> v50.0.1

The only non-wheel-hash lines in the uv.lock diff are the version and the requires-dist specifier:

-    { name = "cryptography", specifier = ">=48.0.1" },
+    { name = "cryptography", specifier = ">=50.0.0" },
-version = "48.0.1"
+version = "50.0.1"

Note it landed on 50.0.1, not 50.0.0 — that's the newest patch (uploaded 2026-08-25) and it satisfies the >=50.0.0 floor.

Safety assessment: safe to merge — high confidence

I'll be concrete about why, because "major version bump" normally warrants caution and here it genuinely doesn't.

1. Nothing in this repo imports cryptography directly. A grep across backend/**/*.py for cryptography, hazmat, pkcs7, serialization, and x509 returns zero real hits. The only x509 matches are auth_provider_x509_cert_url — a Django URLField in google_api/models.py:53, i.e. a string column, not a certificate parse.

2. Every 50.0.0 breaking change is in a code path we don't reach. Going through the changelog item by item:

50.0.0 change	Our exposure
PKCS#7 Bleichenbacher oracle fix (CVE-2026-69247)	None — no pkcs7 usage anywhere
FFDH / asymmetric.dh deprecated	None — no DH usage
Stricter SCT-list, InvalidityDate, OCSP version, BIT STRING unused-bits parsing	None — we never load certs, CRLs, or OCSP responses
xof() on SHAKE128/256, Cobblestone recipe, AWS-LC additions	Purely additive

3. The transitive consumers all declare it under optional extras that we don't enable. This is the part I checked most carefully, since a transitive pin is the usual way a bump like this bites:

PyJWT       -> cryptography>=3.4.0   ; extra == "crypto"
celery      -> cryptography==46.0.5  ; extra == "auth"
django-ses  -> cryptography>=36.0.2  ; extra == "bounce" or extra == "events"
google-auth -> cryptography>=38.0.3  ; extra == "pyopenssl" / "enterprise-cert"
oauthlib    -> cryptography>=3.0.0   ; extra == "rsa" / "signedtoken"
pypdf       -> cryptography>3.0      ; extra == "crypto"
redis       -> cryptography>=36.0.1  ; extra == "ocsp"

pyproject.toml installs celery==5.6.3, django-ses==4.1.1, redis[hiredis]==8.1.0, PyJWT>=2.8.0, pypdf>=6.13.3 — none of those extras are enabled. That matters most for celery, which pins cryptography==46.0.5 exactly; because celery[auth] isn't installed, that pin is inert and doesn't conflict with 50.x. (uv resolving without a conflict confirms it.)

4. The one live crypto path is unaffected. Password-reset tokens use JWT with HS256 (api/users/mutations/request_reset_password.py:61, api/users/mutations/reset_password.py:38) — HMAC-SHA256, which PyJWT implements in pure Python via hashlib and never routes through cryptography. The 89 tests in api/users/tests/ pass.

Verification run

Check	Result
uv sync	cryptography==48.0.1 → cryptography==50.0.1, imports fine (bundled OpenSSL 4.0.2)
uv run pytest visa/tests/test_tasks.py api/users/tests/	89 passed
uv run pytest google_api/ integrations/ pretix/	73 passed
uv run python manage.py check --settings=pycon.settings.test	App loads; 5 pre-existing fields.E010 I18n-default notices
uv run mypy .	3 errors — pre-existing
ruff check / ruff format --check	1 unused import + 19 files needing reformat — pre-existing

I picked visa/ (the pypdf/PDF path) and google_api/+integrations/+pretix/ (the OAuth/HTTP paths) as the modules most likely to touch crypto indirectly. Leaving the full suite to CI as you suggested.

On the mypy/ruff failures: they're not from this PR. git status shows the working tree only modified backend/uv.lock, and git diff --name-only origin/main...HEAD shows only backend/pyproject.toml — every Python source file is byte-identical to main. The failures are in badge_scanner/models.py, sponsors/tests/test_tasks.py, submissions/tests/*, visa/tests/test_tasks.py and friends, all untouched here.

Two things worth knowing (neither blocks merge)

Wheel platform coverage narrowed. 48.0.1 shipped macosx_10_9_universal2 and win32 wheels; 50.0.1 ships macosx_11_0_arm64 and win_amd64 only. So there's no prebuilt macOS x86_64 wheel any more — anyone developing on an Intel Mac outside Docker would have to build from sdist, which needs a Rust toolchain. Doesn't affect CI, Docker, or production (all linux x86_64/aarch64, fully covered).

Dependabot will stop auto-rebasing this PR, since its description says it only resolves conflicts "as long as you don't alter it yourself" and I've now pushed to the branch. If it goes stale, @dependabot recreate will rebuild it — though that would also drop this lock file commit, so it'd need redoing.

Not done

I didn't run the full backend test suite or the frontend checks — the frontend is untouched by this change, and per your note the full suite is CI's job. The Vercel failure showing above predates this commit and is a frontend deployment, unrelated to a Python dependency.
• Branch: dependabot/pip/backend/cryptography-gte-50.0.0