Security fixes for CVE-2025-66471 and CVE-2025-66418

CVE-2025-66418.patch

@@ -0,0 +1,75 @@
+From cfd0b102a8546b82c6e7616eded3cba870e199c7 Mon Sep 17 00:00:00 2001
+From: Illia Volochii <illia.volochii@gmail.com>
+Date: Fri, 5 Dec 2025 16:41:33 +0200
+Subject: [PATCH] Security fix for CVE-2025-66418
+
+* Add a hard-coded limit for the decompression chain
+
+* Reuse new list
+
+(cherry picked from commit 24d7b67eac89f94e11003424bcf0d8f7b72222a8)
+---
+ changelog/GHSA-gm62-xv2j-4w53.security.rst |  4 ++++
+ src/urllib3/response.py                    | 12 +++++++++++-
+ test/test_response.py                      | 10 ++++++++++
+ 3 files changed, 25 insertions(+), 1 deletion(-)
+ create mode 100644 changelog/GHSA-gm62-xv2j-4w53.security.rst
+
+diff --git a/changelog/GHSA-gm62-xv2j-4w53.security.rst b/changelog/GHSA-gm62-xv2j-4w53.security.rst
+new file mode 100644
+index 00000000..6646eaa3
+--- /dev/null
++++ b/changelog/GHSA-gm62-xv2j-4w53.security.rst
+@@ -0,0 +1,4 @@
++Fixed a security issue where an attacker could compose an HTTP response with
++virtually unlimited links in the ``Content-Encoding`` header, potentially
++leading to a denial of service (DoS) attack by exhausting system resources
++during decoding. The number of allowed chained encodings is now limited to 5.
+diff --git a/src/urllib3/response.py b/src/urllib3/response.py
+index 6fb88391..c5ffa803 100644
+--- a/src/urllib3/response.py
++++ b/src/urllib3/response.py
+@@ -219,8 +219,18 @@ class MultiDecoder(object):
+         they were applied.
+     """
+ 
++    # Maximum allowed number of chained HTTP encodings in the
++    # Content-Encoding header.
++    max_decode_links = 5
++
+     def __init__(self, modes):
+-        self._decoders = [_get_decoder(m.strip()) for m in modes.split(",")]
++        encodings = [m.strip() for m in modes.split(",")]
++        if len(encodings) > self.max_decode_links:
++            raise DecodeError(
++                "Too many content encodings in the chain: "
++                f"{len(encodings)} > {self.max_decode_links}"
++            )
++        self._decoders = [_get_decoder(e) for e in encodings]
+ 
+     def flush(self):
+         return self._decoders[0].flush()
+diff --git a/test/test_response.py b/test/test_response.py
+index 0d4b8ea8..47f853a2 100644
+--- a/test/test_response.py
++++ b/test/test_response.py
+@@ -534,6 +534,16 @@ class TestResponse(object):
+         assert r.read(9 * 37) == b"foobarbaz" * 37
+         assert r.read() == b""
+ 
++    def test_read_multi_decoding_too_many_links(self):
++        fp = BytesIO(b"foo")
++        with pytest.raises(
++            DecodeError, match="Too many content encodings in the chain: 6 > 5"
++        ):
++            HTTPResponse(
++                fp,
++                headers={"content-encoding": "gzip, deflate, br, zstd, gzip, deflate"},
++            )
++
+     def test_body_blob(self):
+         resp = HTTPResponse(b"foo")
+         assert resp.data == b"foo"
+-- 
+2.52.0
+

python-urllib3.spec

@@ -6,7 +6,7 @@
 
 Name:           python-%{srcname}
 Version:        1.26.5
-Release:        6%{?dist}
+Release:        7%{?dist}
 Summary:        Python HTTP library with thread-safe connection pooling and file post
 
 License:        MIT
@@ -43,6 +43,9 @@ Patch3: Add-server_hostname-to-SSL_KEYWORDS.patch
 # Upstream fix: https://github.com/urllib3/urllib3/commit/40b6d1605814dd1db0a46e202d6e56f2e4c9a468
 Patch4: CVE-2024-37891.patch
 
+Patch5: CVE-2025-66471.patch
+Patch6: CVE-2025-66418.patch
+
 %description
 Python HTTP module with connection pooling and file POST abilities.
 
@@ -145,6 +148,11 @@ ln -s %{python3_sitelib}/__pycache__/six.cpython-%{python3_version_nodots}.pyc \
 
 
 %changelog
+* Tue Jan 27 2026 Miro Hrončok <mhroncok@redhat.com> - 1.26.5-7
+- Security fix for CVE-2025-66471
+- Security fix for CVE-2025-66418
+Resolves: RHEL-142750, RHEL-139398
+
 * Tue Jun 18 2024 Tomáš Hrnčiar <thrnciar@redhat.com> - 1.26.5-6
 - Security fix for CVE-2024-37891
 - Backport upstream patch to fix TypeError for http connection if the PoolManager