File CVE-2025-66418.patch of Package python-urllib3.42446

From 24d7b67eac89f94e11003424bcf0d8f7b72222a8 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] Merge commit from fork

* Add a hard-coded limit for the decompression chain

* Reuse new list
---
 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

Index: urllib3-2.5.0/src/urllib3/response.py
===================================================================
--- urllib3-2.5.0.orig/src/urllib3/response.py
+++ urllib3-2.5.0/src/urllib3/response.py
@@ -342,8 +342,18 @@ class MultiDecoder(ContentDecoder):
         they were applied.
     """
 
+    # Maximum allowed number of chained HTTP encodings in the
+    # Content-Encoding header.
+    max_decode_links = 5
+
     def __init__(self, modes: str) -> None:
-        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) -> bytes:
         return self._decoders[0].flush()
Index: urllib3-2.5.0/test/test_response.py
===================================================================
--- urllib3-2.5.0.orig/test/test_response.py
+++ urllib3-2.5.0/test/test_response.py
@@ -843,6 +843,16 @@ class TestResponse:
         assert r.read(9 * 37) == b"foobarbaz" * 37
         assert r.read() == b""
 
+    def test_read_multi_decoding_too_many_links(self) -> None:
+        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) -> None:
         resp = HTTPResponse(b"foo")
         assert resp.data == b"foo"