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This release bundles five security fixes plus three additional hardening / spec-compliance changes. We recommend all users upgrade.
Security
GHSA-xgmm-8j9v-c9wx — JWK JSON accepted as HMAC secret (algorithm confusion). HMACAlgorithm.prepare_key previously rejected PEM- and SSH-formatted asymmetric keys but did not catch a JWK passed as a raw JSON string. In a verifier configured with both symmetric and asymmetric algorithms in algorithms=[…] and a raw-JSON JWK as the key, an attacker could forge HS256 tokens using the JWK text as the HMAC secret. The guard has been extended to reject any JWK-shaped JSON. Reported by @aradona91.
GHSA-jq35-7prp-9v3f — Algorithm allow-list bypass with PyJWK / PyJWKClient. When verifying with a PyJWK, the caller's algorithms=[…] allow-list was checked against the token header alg as a string only; actual verification used the algorithm bound to the PyJWK. An attacker who controlled a registered JWKS key could sign with one algorithm and advertise another on the header. PyJWT now requires the token header alg to match the PyJWK's algorithm before verification. Reported by @sushi-gif.
GHSA-w7vc-732c-9m39 — DoS via base64 decode of unused payload segment when b64=false. For detached-payload JWS (b64=false), the compact-form payload segment was base64-decoded before being discarded in favor of the caller-supplied detached_payload. An attacker could inflate the unused segment to force CPU + memory cost without holding a valid signature. The segment is now required to be empty per RFC 7515 Appendix F, and is no longer decoded. Reported by @thesmartshadow.
GHSA-993g-76c3-p5m4 — PyJWKClient accepts non-HTTP(S) URIs. PyJWKClient.fetch_data passed its URI to urllib.request.urlopen, which by default also handles file://, ftp://, and data: schemes. An application that fed an attacker-influenced URI into PyJWKClient could be coerced into reading local files or reaching other unintended schemes. PyJWKClient now rejects any URI whose scheme isn't http or https. Reported by @KEIJOT.
GHSA-fhv5-28vv-h8m8 — PyJWKClient cache wiped on fetch error. A finally-block put(jwk_set=None) cleared the JWK Set cache whenever a fetch raised, turning a transient JWKS-endpoint outage into application-wide auth failure. The cache write was moved into the success path; transient errors no longer evict valid cached keys. Reported by @eddieran.
Fixed
Reject empty HMAC keys outright in HMACAlgorithm.prepare_key with InvalidKeyError instead of accepting them with only a warning. Defends against the os.getenv("JWT_SECRET", "") footgun. Thanks to @SnailSploit and @spartan8806 for the reports.
Forward per-call options (including enforce_minimum_key_length) from PyJWT.decode through to PyJWS._verify_signature. The option was previously silently dropped between the two layers, so it only took effect when set on the PyJWT instance. Thanks to @WLUB for the report.
RFC 7797 §3 compliance for b64=false: the encoder now auto-adds "b64" to crit, and the decoder rejects tokens that set b64=false without listing it in crit. Thanks to @MachineLearning-Nerd for the report.
Changed
Migrate the dev, docs, and tests package extras to dependency groups, by @kurtmckee in #1152.
Upgrade notes
Most fixes are invisible to correctly-configured callers. A few behavioral changes you may encounter:
Empty HMAC keys now raise. If your app passed "" or b"" as a secret (often via a missing env var, e.g. os.getenv("JWT_SECRET", "")), encode/decode will now raise InvalidKeyError. This is the intended behavior — fix the configuration.
PyJWK decoding now requires the token's alg to match the JWK's algorithm. Previously a mismatch was silently honored if the header alg appeared in the allow-list. Tokens that relied on this mismatch will now fail with InvalidAlgorithmError.
PyJWKClient now rejects non-HTTP(S) URIs at construction time. Tests or dev environments that fetched JWKS from file:// URIs need to switch to a local HTTP server or load the JWKS by other means (e.g. construct PyJWKSet.from_dict(...) directly).
b64=false tokens are now strictly RFC 7515 / 7797 compliant. Tokens with a non-empty compact-form payload segment, or that omit "b64" from crit, will be rejected. PyJWT-produced tokens always satisfy both invariants, so round-trips through PyJWT are unaffected.
enforce_minimum_key_length set per-call now takes effect. Callers who passed options={"enforce_minimum_key_length": True} to jwt.decode() previously got no enforcement; they will now get InvalidKeyError on undersized keys, as documented.
- Reject JWK JSON documents passed as raw HMAC secrets in
``HMACAlgorithm.prepare_key`` to close an algorithm-confusion gap that
the existing PEM/SSH guard did not cover. Reported by @aradona91 in
`GHSA-xgmm-8j9v-c9wx <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-xgmm-8j9v-c9wx>`__.
- Bind the JWT header ``alg`` to ``PyJWK.algorithm_name`` during
verification so the caller's ``algorithms=[...]`` allow-list cannot be
bypassed when decoding with a ``PyJWK`` / ``PyJWKClient`` key. Reported
by @sushi-gif in `GHSA-jq35-7prp-9v3f <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jq35-7prp-9v3f>`__.
- Reject non-``http(s)`` URI schemes in ``PyJWKClient`` so attacker-
influenced URIs cannot read local files or reach unintended schemes via
urllib's default ``file://`` / ``ftp://`` / ``data:`` handlers. Reported
by @KEIJOT in `GHSA-993g-76c3-p5m4 <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-993g-76c3-p5m4>`__.
- Preserve the cached JWK Set on fetch errors in ``PyJWKClient.fetch_data``.
The previous ``finally``-block ``put(None)`` pattern cleared the cache
on any transient outage, turning one bad JWKS request into application-
wide auth failure. Reported by @eddieran in `GHSA-fhv5-28vv-h8m8 <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-fhv5-28vv-h8m8>`__.
- Skip the unconditional base64 decode of the compact-form payload segment
when ``b64=false`` is set in the protected header, and require that
segment to be empty (RFC 7515 Appendix F detached form). Closes an
unauthenticated DoS amplifier. Reported by @thesmartshadow in
`GHSA-w7vc-732c-9m39 <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-w7vc-732c-9m39>`__.
Fixed
- Reject empty HMAC keys outright in ``HMACAlgorithm.prepare_key`` with
``InvalidKeyError`` instead of accepting them with only a warning.
Thanks to @SnailSploit and @spartan8806 for independently flagging the
footgun.
- Forward per-call ``options`` (including ``enforce_minimum_key_length``)
from ``PyJWT.decode`` through to ``PyJWS._verify_signature`` so the
option actually takes effect when set at the call site rather than only
on the ``PyJWT`` instance. Thanks to @WLUB for the report.
- RFC 7797 §3 compliance for ``b64=false``: the encoder now auto-adds
``"b64"`` to the ``crit`` header parameter, and the decoder rejects
tokens that set ``b64=false`` without listing it in ``crit``. Thanks to
@MachineLearning-Nerd for the report.
Changed
Migrate the dev, docs, and tests package extras to dependency groups by @kurtmckee in [#1152](https://github.com/jpadilla/pyjwt/issues/1152) <https://github.com/jpadilla/pyjwt/pull/1152>__
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pyjwt
[>= 2.10.dev0, < 2.11]
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Bumps pyjwt from 2.12.1 to 2.13.0.
Release notesSourced from pyjwt's releases.
2.13.0
PyJWT 2.13.0 — Security Release
This release bundles five security fixes plus three additional hardening / spec-compliance changes. We recommend all users upgrade.
Security
GHSA-xgmm-8j9v-c9wx — JWK JSON accepted as HMAC secret (algorithm confusion). HMACAlgorithm.prepare_key previously rejected PEM- and SSH-formatted asymmetric keys but did not catch a JWK passed as a raw JSON string. In a verifier configured with both symmetric and asymmetric algorithms in algorithms=[…] and a raw-JSON JWK as the key, an attacker could forge HS256 tokens using the JWK text as the HMAC secret. The guard has been extended to reject any JWK-shaped JSON. Reported by @aradona91.
GHSA-jq35-7prp-9v3f — Algorithm allow-list bypass with PyJWK / PyJWKClient. When verifying with a PyJWK, the caller's algorithms=[…] allow-list was checked against the token header alg as a string only; actual verification used the algorithm bound to the PyJWK. An attacker who controlled a registered JWKS key could sign with one algorithm and advertise another on the header. PyJWT now requires the token header alg to match the PyJWK's algorithm before verification. Reported by @sushi-gif.
GHSA-w7vc-732c-9m39 — DoS via base64 decode of unused payload segment when b64=false. For detached-payload JWS (b64=false), the compact-form payload segment was base64-decoded before being discarded in favor of the caller-supplied detached_payload. An attacker could inflate the unused segment to force CPU + memory cost without holding a valid signature. The segment is now required to be empty per RFC 7515 Appendix F, and is no longer decoded. Reported by @thesmartshadow.
GHSA-993g-76c3-p5m4 — PyJWKClient accepts non-HTTP(S) URIs. PyJWKClient.fetch_data passed its URI to urllib.request.urlopen, which by default also handles file://, ftp://, and data: schemes. An application that fed an attacker-influenced URI into PyJWKClient could be coerced into reading local files or reaching other unintended schemes. PyJWKClient now rejects any URI whose scheme isn't http or https. Reported by @KEIJOT.
GHSA-fhv5-28vv-h8m8 — PyJWKClient cache wiped on fetch error. A finally-block put(jwk_set=None) cleared the JWK Set cache whenever a fetch raised, turning a transient JWKS-endpoint outage into application-wide auth failure. The cache write was moved into the success path; transient errors no longer evict valid cached keys. Reported by @eddieran.
Fixed
Changed
Upgrade notes
Most fixes are invisible to correctly-configured callers. A few behavioral changes you may encounter:
Full changelog: jpadilla/pyjwt@2.12.1...2.13.0
ChangelogSourced from pyjwt's changelog.
v2.13.0 <https://github.com/jpadilla/pyjwt/compare/2.12.1...2.13.0>__
Security
- Reject JWK JSON documents passed as raw HMAC secrets in ``HMACAlgorithm.prepare_key`` to close an algorithm-confusion gap that the existing PEM/SSH guard did not cover. Reported by @aradona91 in `GHSA-xgmm-8j9v-c9wx <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-xgmm-8j9v-c9wx>`__. - Bind the JWT header ``alg`` to ``PyJWK.algorithm_name`` during verification so the caller's ``algorithms=[...]`` allow-list cannot be bypassed when decoding with a ``PyJWK`` / ``PyJWKClient`` key. Reported by @sushi-gif in `GHSA-jq35-7prp-9v3f <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jq35-7prp-9v3f>`__. - Reject non-``http(s)`` URI schemes in ``PyJWKClient`` so attacker- influenced URIs cannot read local files or reach unintended schemes via urllib's default ``file://`` / ``ftp://`` / ``data:`` handlers. Reported by @KEIJOT in `GHSA-993g-76c3-p5m4 <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-993g-76c3-p5m4>`__. - Preserve the cached JWK Set on fetch errors in ``PyJWKClient.fetch_data``. The previous ``finally``-block ``put(None)`` pattern cleared the cache on any transient outage, turning one bad JWKS request into application- wide auth failure. Reported by @eddieran in `GHSA-fhv5-28vv-h8m8 <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-fhv5-28vv-h8m8>`__. - Skip the unconditional base64 decode of the compact-form payload segment when ``b64=false`` is set in the protected header, and require that segment to be empty (RFC 7515 Appendix F detached form). Closes an unauthenticated DoS amplifier. Reported by @thesmartshadow in `GHSA-w7vc-732c-9m39 <https://github.com/jpadilla/pyjwt/security/advisories/GHSA-w7vc-732c-9m39>`__.Fixed
- Reject empty HMAC keys outright in ``HMACAlgorithm.prepare_key`` with ``InvalidKeyError`` instead of accepting them with only a warning. Thanks to @SnailSploit and @spartan8806 for independently flagging the footgun. - Forward per-call ``options`` (including ``enforce_minimum_key_length``) from ``PyJWT.decode`` through to ``PyJWS._verify_signature`` so the option actually takes effect when set at the call site rather than only on the ``PyJWT`` instance. Thanks to @WLUB for the report. - RFC 7797 §3 compliance for ``b64=false``: the encoder now auto-adds ``"b64"`` to the ``crit`` header parameter, and the decoder rejects tokens that set ``b64=false`` without listing it in ``crit``. Thanks to @MachineLearning-Nerd for the report.Changed
- Migrate the dev, docs, and tests package extras to dependency groups by @kurtmckee in [#1152](https://github.com/jpadilla/pyjwt/issues/1152) <https://github.com/jpadilla/pyjwt/pull/1152>__
CommitsMost Recent Ignore Conditions Applied to This Pull Request
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