python-jwcrypto/SOURCES/0001-Address-potential-DoS-with-high-compression-ratio_rhel#28697.patch
2024-05-23 10:02:03 +03:00

75 lines
2.5 KiB
Diff

From 90477a3b6e73da69740e00b8161f53fea19b831f Mon Sep 17 00:00:00 2001
From: Simo Sorce <simo@redhat.com>
Date: Tue, 5 Mar 2024 16:57:17 -0500
Subject: [PATCH] Address potential DoS with high compression ratio
Fixes CVE-2024-28102
Signed-off-by: Simo Sorce <simo@redhat.com>
---
jwcrypto/jwe.py | 7 +++++++
jwcrypto/tests.py | 26 ++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/jwcrypto/jwe.py b/jwcrypto/jwe.py
index 9412881..5df500b 100644
--- a/jwcrypto/jwe.py
+++ b/jwcrypto/jwe.py
@@ -9,5 +10,8 @@
from jwcrypto.jwa import JWA
+# Limit the amount of data we are willing to decompress by default.
+default_max_compressed_size = 256 * 1024
+
# RFC 7516 - 4.1
# name: (description, supported?)
@@ -374,6 +374,10 @@ def _decrypt(self, key, ppe):
compress = jh.get('zip', None)
if compress == 'DEF':
+ if len(data) > default_max_compressed_size:
+ raise InvalidJWEData(
+ 'Compressed data exceeds maximum allowed'
+ 'size' + f' ({default_max_compressed_size})')
self.plaintext = zlib.decompress(data, -zlib.MAX_WBITS)
elif compress is None:
self.plaintext = data
diff --git a/jwcrypto/tests.py b/jwcrypto/tests.py
index bb2ff10..59049f8 100644
--- a/jwcrypto/tests.py
+++ b/jwcrypto/tests.py
@@ -1196,6 +1196,32 @@ def test_pbes2_hs256_aeskw_custom_params(self):
check.deserialize(enc, key)
self.assertEqual(b'plain', check.payload)
+ def test_jwe_decompression_max(self):
+ key = jwk.JWK(kty='oct', k=base64url_encode(b'A' * (128 // 8)))
+ payload = '{"u": "' + "u" * 400000000 + '", "uu":"' \
+ + "u" * 400000000 + '"}'
+ protected_header = {
+ "alg": "A128KW",
+ "enc": "A128GCM",
+ "typ": "JWE",
+ "zip": "DEF",
+ }
+ enc = jwe.JWE(payload.encode('utf-8'),
+ recipient=key,
+ protected=protected_header).serialize(compact=True)
+ with self.assertRaises(jwe.InvalidJWEData):
+ check = jwe.JWE()
+ check.deserialize(enc)
+ check.decrypt(key)
+
+ defmax = jwe.default_max_compressed_size
+ jwe.default_max_compressed_size = 1000000000
+ # ensure we can eraise the limit and decrypt
+ check = jwe.JWE()
+ check.deserialize(enc)
+ check.decrypt(key)
+ jwe.default_max_compressed_size = defmax
+
class JWATests(unittest.TestCase):
def test_jwa_create(self):