Address potential DoS with high compression ratio

Resolves: RHEL-28697

Signed-off-by: Rafael Guterres Jeffman <rjeffman@redhat.com>
This commit is contained in:
Rafael Guterres Jeffman 2024-04-03 12:37:32 -03:00
parent f1bb6a18ff
commit 75872feb88
2 changed files with 82 additions and 1 deletions

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@ -0,0 +1,74 @@
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):

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@ -16,13 +16,15 @@
Name: python-%{srcname}
Version: 0.5.0
Release: 1.1%{?dist}
Release: 2%{?dist}
Summary: Implements JWK, JWS, JWE specifications using python-cryptography
License: LGPLv3+
URL: https://github.com/latchset/%{srcname}
Source0: https://github.com/latchset/%{srcname}/releases/download/v%{version}/%{srcname}-%{version}.tar.gz
Patch1: 0001-Address-potential-DoS-with-high-compression-ratio_rhel#28697.patch
BuildArch: noarch
%if %{with python2}
BuildRequires: python2-devel
@ -64,6 +66,7 @@ Implements JWK, JWS, JWE specifications using python-cryptography
%prep
%setup -q -n %{srcname}-%{version}
%autopatch -p 1
%build
%if %{with python2}
@ -114,6 +117,10 @@ rm -rf %{buildroot}/usr/share/doc/jwcrypto
%changelog
* Wed Apr 03 2024 Rafael Jeffman <rjeffman@redhat.com> - 0.5.0-2
- Address potential DoS with high compression ratio
Resolves: RHEL-28697
* Fri Jun 17 2022 Christian Heimes <cheimes@redhat.com> - 0.5.0-1.1
- Bump dist to solve version sorting issue, fixes RHBZ#2097800