python3-pyjwt: Fix CVE-2026-48525

This patch applies the upstream 2.13.0 backport for CVE-2026-48525. The upstream fix commit is referenced in [1], and the public CVE advisory is referenced in [2]. [1] https://github.com/jpadilla/pyjwt/commit/95791b1759b8aa4f2203575d344d5c78564cdc81 [2] https://github.com/advisories/GHSA-w7vc-732c-9m39 Signed-off-by: Hetvi Thakar <hthakar@cisco.com> Signed-off-by: Anuj Mittal <anuj.mittal@oss.qualcomm.com>
2026-08-30 00:33:19 +00:00 · 2026-08-19 04:00:14 -07:00
parent 8a6759f036
commit 5fd7815f34
2 changed files with 147 additions and 0 deletions
@@ -0,0 +1,146 @@
+From e6152fb27dd439bf4541aab9b26a93134c48135f Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Jos=C3=A9=20Padilla?= <jpadilla@users.noreply.github.com>
+Date: Thu, 21 May 2026 14:11:10 -0400
+Subject: [PATCH] Bundle security fixes and hardening into 2.13.0
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Security:
+- `HMACAlgorithm.prepare_key` rejects JWK JSON documents passed as raw
+  HMAC secrets to close an algorithm-confusion gap not covered by the
+  existing PEM/SSH guard. Reported by @aradona91 in 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.
+- Skip the unconditional base64 decode of the compact-form payload
+  segment when `b64=false` is set, 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.
+- `PyJWKClient` rejects any URI whose scheme is not `http` or `https` 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.
+- 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. Reported by @eddieran in GHSA-fhv5-28vv-h8m8.
+
+Fixes:
+- Reject empty HMAC keys outright in `HMACAlgorithm.prepare_key` with
+  `InvalidKeyError` instead of accepting them with only a warning.
+  Hardening prompted by reports from @SnailSploit and @spartan8806.
+- Forward per-call `options` (including `enforce_minimum_key_length`)
+  from `PyJWT.decode` through to `PyJWS._verify_signature`. Thanks to
+  @WLUB.
+- RFC 7797 §3 compliance for `b64=false`: encoder auto-adds `"b64"` to
+  `crit`; decoder rejects tokens that set `b64=false` without listing
+  it in `crit`. Thanks to @MachineLearning-Nerd.
+
+CVE: CVE-2026-48525
+Upstream-Status: Backport [https://github.com/jpadilla/pyjwt/commit/95791b1759b8aa4f2203575d344d5c78564cdc81]
+
+Backport Changes:
+- Split out the b64=false payload-decoding DoS fix because the upstream
+  commit bundles multiple CVEs.
+- Omitted CHANGELOG.rst because it conflicted and is release documentation.
+- Carried the focused
+  `test_decode_b64_false_rejects_non_empty_payload_segment` regression test.
+  Omitted other tests/test_api_jws.py hunks for unrelated bundled fixes.
+- Omitted the 2.13.0 version bump and other bundled fixes; applicable CVE
+  fixes are carried in separate patches.
+
+(cherry picked from commit 95791b1759b8aa4f2203575d344d5c78564cdc81)
+Signed-off-by: Hetvi Thakar <hthakar@cisco.com>
+---
+ jwt/api_jws.py        | 22 ++++++++++++++++++----
+ tests/test_api_jws.py | 36 +++++++++++++++++++++++++++++++++++-
+ 2 files changed, 53 insertions(+), 5 deletions(-)
+
+diff --git a/jwt/api_jws.py b/jwt/api_jws.py
+index 91d2ae3..5a91bce 100644
+--- a/jwt/api_jws.py
+++ b/jwt/api_jws.py
+@@ -317,10 +317,24 @@ class PyJWS:
+         if not isinstance(header, dict):
+             raise DecodeError("Invalid header string: must be a json object")
+ 
+-        try:
+-            payload = base64url_decode(payload_segment)
+-        except (TypeError, binascii.Error) as err:
+-            raise DecodeError("Invalid payload padding") from err
+        if header.get("b64", True) is False:
+            # Detached payload form (RFC 7515 Appendix F): the compact-form
+            # payload segment must be empty; the caller supplies the actual
+            # payload via the `detached_payload` argument in decode_complete.
+            # Skipping the base64 decode here removes an unauthenticated work
+            # amplifier — otherwise an attacker can inflate the unused
+            # segment to force CPU + memory cost before the signature is
+            # even checked.
+            if payload_segment:
+                raise DecodeError(
+                    "Payload segment must be empty when 'b64' is false."
+                )
+            payload = b""
+        else:
+            try:
+                payload = base64url_decode(payload_segment)
+            except (TypeError, binascii.Error) as err:
+                raise DecodeError("Invalid payload padding") from err
+ 
+         try:
+             signature = base64url_decode(crypto_segment)
+diff --git a/tests/test_api_jws.py b/tests/test_api_jws.py
+index 0715b9e..01de813 100644
+--- a/tests/test_api_jws.py
+++ b/tests/test_api_jws.py
+@@ -12,7 +12,7 @@ from jwt.exceptions import (
+     InvalidSignatureError,
+     InvalidTokenError,
+ )
+-from jwt.utils import base64url_decode
+from jwt.utils import base64url_decode, base64url_encode
+ from jwt.warnings import RemovedInPyjwt3Warning
+ 
+ from .utils import crypto_required, key_path, no_crypto_required
+@@ -984,6 +984,40 @@ class TestJWS:
+         assert "b64" not in msg_header_obj
+         assert msg_payload
+ 
+    def test_decode_b64_false_rejects_non_empty_payload_segment(
+        self, jws: PyJWS, payload: bytes
+    ) -> None:
+        # RFC 7515 Appendix F detached form: when b64=false, the compact-
+        # serialization payload segment must be empty. PyJWT must reject a
+        # non-empty middle segment without doing any base64-decoding work
+        # on it — that decode used to be the unauthenticated DoS amplifier.
+        secret = "secret"
+        import hmac as _hmac
+        import hashlib as _hashlib
+
+        header_obj = {
+            "typ": "JWT",
+            "alg": "HS256",
+            "b64": False,
+            "crit": ["b64"],
+        }
+        header_b64 = base64url_encode(
+            json.dumps(header_obj, separators=(",", ":")).encode()
+        )
+        # Stuff the middle segment with arbitrary attacker-controlled bytes.
+        # This should be rejected without being base64-decoded.
+        attacker_segment = b"A" * 1024
+        signing_input = b".".join([header_b64, payload])
+        sig = _hmac.new(secret.encode(), signing_input, _hashlib.sha256).digest()
+        token = b".".join(
+            [header_b64, attacker_segment, base64url_encode(sig)]
+        ).decode()
+
+        with pytest.raises(DecodeError, match="Payload segment must be empty"):
+            jws.decode(
+                token, secret, algorithms=["HS256"], detached_payload=payload
+            )
+
+     def test_decode_detached_content_without_proper_argument(self, jws: PyJWS) -> None:
+         example_jws = (
+             "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiIsImI2NCI6ZmFsc2V9"
@@ -8,6 +8,7 @@ LIC_FILES_CHKSUM = "file://LICENSE;md5=e4b56d2c9973d8cf54655555be06e551"
 SRC_URI += "file://CVE-2026-48522.patch \
           file://CVE-2026-48523.patch \
           file://CVE-2026-48524.patch \
+           file://CVE-2026-48525.patch \
           "

 SRC_URI[sha256sum] = "c74a7a2adf861c04d002db713dd85f84beb242228e671280bf709d765b03672b"