microsoft · Ratiranjan5 · Aug 3, 2026
@@ -0,0 +1,196 @@
+From 10dfb6b9005484578b386f64b9f36982e3dc6679 Mon Sep 17 00:00:00 2001
+From: Damian Shaw <damian.peter.shaw@gmail.com>
+Date: Tue, 30 Jun 2026 21:52:39 -0400
+Subject: [PATCH] Fix Link.filename decoding URL path twice (#14110)
+
+Link already percent-decodes the URL path into `self._path`, but
+`Link.filename` decoded the basename again, so a doubly-encoded
+separator was decoded twice: `%252F` became `%2F` in `__init__`, then
+`/` in `filename`, turning the single component `a%2Fb.whl` into
+`a/b.whl`.
+
+Drop the second decode, and add a `join_within_directory` helper so the
+download-path joins treat the name as a single path component.
+
+Upstream Patch Reference: https://github.com/pypa/pip/commit/10dfb6b9005484578b386f64b9f36982e3dc6679.patch
+---
+ pip/_internal/models/link.py        | 63 +++++++++++++++++++++++------
+ pip/_internal/network/download.py   | 18 ++++++---
+ pip/_internal/operations/prepare.py |  6 +--
+ 3 files changed, 67 insertions(+), 20 deletions(-)
+
+diff --git a/pip/_internal/models/link.py b/pip/_internal/models/link.py
+index 27ad016..de2c9aa 100644
+--- a/pip/_internal/models/link.py
++++ b/pip/_internal/models/link.py
+@@ -13,6 +13,7 @@ from typing import (
+     List,
+     Mapping,
+     NamedTuple,
++    NewType,
+     Optional,
+     Tuple,
+     Union,
+@@ -35,6 +36,49 @@ if TYPE_CHECKING:
+ logger = logging.getLogger(__name__)
+
+
++# A single path component: percent-decoded once and reduced to a basename, so it
++# contains no path separator and is not a ``.`` or ``..`` reference. The empty
++# string means "no component".
++PathComponent = NewType("PathComponent", str)
++
++
++def _to_path_component(name: str) -> PathComponent:
++    """Reduce ``name`` to a single path component, or ``""`` if it has none.
++
++    ``os.path.basename`` drops any directory part, drive letter, or separator;
++    a ``.``, ``..``, or empty result is not a component and becomes ``""``.
++    """
++    name = os.path.basename(name)
++    if name in ("", os.curdir, os.pardir):
++        return PathComponent("")
++
++    return PathComponent(name)
++
++
++def as_path_component(name: str) -> PathComponent:
++    """Like ``_to_path_component`` but reject the empty result.
++
++    Use where a file is about to be written, so a missing name is an error
++    rather than a silent fallback to the directory itself.
++    """
++    component = _to_path_component(name)
++    if not component:
++        raise ValueError(f"Unexpected file name derived from URL: {name!r}")
++
++    return component
++
++
++def join_within_directory(directory: str, component: PathComponent) -> str:
++    """Join a single path ``component`` onto ``directory``.
++
++    ``component`` is a :data:`PathComponent`, so by type it has no separator and
++    is not a ``.`` or ``..`` reference; the result can never escape ``directory``.
++    Requiring ``PathComponent`` rather than ``str`` lets the type checker enforce
++    at the call site that the name was reduced to a safe component beforehand.
++    """
++    return os.path.join(directory, component)
++
++
+ # Order matters, earlier hashes have a precedence over later hashes for what
+ # we will pick to use.
+ _SUPPORTED_HASHES = ("sha512", "sha384", "sha256", "sha224", "sha1", "md5")
+@@ -405,18 +449,13 @@ class Link:
+         return self._url
+
+     @property
+-    def filename(self) -> str:
+-        path = self.path.rstrip("/")
+-        name = posixpath.basename(path)
+-        if not name:
+-            # Make sure we don't leak auth information if the netloc
+-            # includes a username and password.
+-            netloc, user_pass = split_auth_from_netloc(self.netloc)
+-            return netloc
+-
+-        name = urllib.parse.unquote(name)
+-        assert name, f"URL {self._url!r} produced no filename"
+-        return name
++    def filename(self) -> PathComponent:
++        name = _to_path_component(posixpath.basename(self.path.rstrip("/")))
++        if name:
++            return name
++
++        # No component in the path; fall back to the netloc, dropping any auth.
++        return _to_path_component(split_auth_from_netloc(self.netloc)[0])
+
+     @property
+     def file_path(self) -> str:
+diff --git a/pip/_internal/network/download.py b/pip/_internal/network/download.py
+index 5c3bce3..21c154d 100644
+--- a/pip/_internal/network/download.py
++++ b/pip/_internal/network/download.py
+@@ -12,7 +12,12 @@ from pip._vendor.requests.models import Response
+ from pip._internal.cli.progress_bars import get_download_progress_renderer
+ from pip._internal.exceptions import NetworkConnectionError
+ from pip._internal.models.index import PyPI
+-from pip._internal.models.link import Link
++from pip._internal.models.link import (
++    Link,
++    PathComponent,
++    as_path_component,
++    join_within_directory,
++)
+ from pip._internal.network.cache import is_from_cache
+ from pip._internal.network.session import PipSession
+ from pip._internal.network.utils import HEADERS, raise_for_status, response_chunks
+@@ -92,11 +97,14 @@ def parse_content_disposition(content_disposition: str, default_filename: str) -
+     return filename or default_filename
+
+
+-def _get_http_response_filename(resp: Response, link: Link) -> str:
++def _get_http_response_filename(resp: Response, link: Link) -> PathComponent:
+     """Get an ideal filename from the given HTTP response, falling back to
+     the link filename if not provided.
++
++    The result is validated as a single path component, so it can be joined onto
++    a download directory without escaping it.
+     """
+-    filename = link.filename  # fallback
++    filename: str = link.filename  # fallback
+     # Have a look at the Content-Disposition header for a better guess
+     content_disposition = resp.headers.get("content-disposition")
+     if content_disposition:
+@@ -110,7 +118,7 @@ def _get_http_response_filename(resp: Response, link: Link) -> str:
+         ext = os.path.splitext(resp.url)[1]
+         if ext:
+             filename += ext
+-    return filename
++    return as_path_component(filename)
+
+
+ def _http_get_download(session: PipSession, link: Link) -> Response:
+@@ -141,7 +149,7 @@ class Downloader:
+             raise
+
+         filename = _get_http_response_filename(resp, link)
+-        filepath = os.path.join(location, filename)
++        filepath = join_within_directory(location, filename)
+
+         chunks = _prepare_download(resp, link, self._progress_bar)
+         with open(filepath, "wb") as content_file:
+diff --git a/pip/_internal/operations/prepare.py b/pip/_internal/operations/prepare.py
+index e6aa344..bfd493b 100644
+--- a/pip/_internal/operations/prepare.py
++++ b/pip/_internal/operations/prepare.py
+@@ -27,7 +27,7 @@ from pip._internal.exceptions import (
+ from pip._internal.index.package_finder import PackageFinder
+ from pip._internal.metadata import BaseDistribution, get_metadata_distribution
+ from pip._internal.models.direct_url import ArchiveInfo
+-from pip._internal.models.link import Link
++from pip._internal.models.link import Link, join_within_directory
+ from pip._internal.models.wheel import Wheel
+ from pip._internal.network.download import BatchDownloader, Downloader
+ from pip._internal.network.lazy_wheel import (
+@@ -191,7 +191,7 @@ def _check_download_dir(
+     """Check download_dir for previously downloaded file with correct hash
+     If a correct file is found return its path else None
+     """
+-    download_path = os.path.join(download_dir, link.filename)
++    download_path = join_within_directory(download_dir, link.filename)
+
+     if not os.path.exists(download_path):
+         return None
+@@ -668,7 +668,7 @@ class RequirementPreparer:
+             # No distribution was downloaded for this requirement.
+             return
+
+-        download_location = os.path.join(self.download_dir, link.filename)
++        download_location = join_within_directory(self.download_dir, link.filename)
+         if not os.path.exists(download_location):
+             shutil.copy(req.local_file_path, download_location)
+             download_path = display_path(download_location)
+-- 
+2.45.4
+
@@ -0,0 +1,198 @@
+From 10dfb6b9005484578b386f64b9f36982e3dc6679 Mon Sep 17 00:00:00 2001
+From: Damian Shaw <damian.peter.shaw@gmail.com>
+Date: Tue, 30 Jun 2026 21:52:39 -0400
+Subject: [PATCH] Fix Link.filename decoding URL path twice (#14110)
+
+Link already percent-decodes the URL path into `self._path`, but
+`Link.filename` decoded the basename again, so a doubly-encoded
+separator was decoded twice: `%252F` became `%2F` in `__init__`, then
+`/` in `filename`, turning the single component `a%2Fb.whl` into
+`a/b.whl`.
+
+Drop the second decode, and add a `join_within_directory` helper so the
+download-path joins treat the name as a single path component.
+
+Upstream Patch Reference: https://github.com/pypa/pip/commit/10dfb6b9005484578b386f64b9f36982e3dc6679.patch
+---
+ pip/_internal/models/link.py        | 63 +++++++++++++++++++++++------
+ pip/_internal/network/download.py   | 20 ++++++---
+ pip/_internal/operations/prepare.py |  6 +--
+ 3 files changed, 69 insertions(+), 20 deletions(-)
+
+diff --git a/pip/_internal/models/link.py b/pip/_internal/models/link.py
+index 295035f..4a2abf2 100644
+--- a/pip/_internal/models/link.py
++++ b/pip/_internal/models/link.py
+@@ -13,6 +13,7 @@ from typing import (
+     TYPE_CHECKING,
+     Any,
+     NamedTuple,
++    NewType,
+ )
+
+ from pip._internal.utils.deprecation import deprecated
+@@ -32,6 +33,49 @@ if TYPE_CHECKING:
+ logger = logging.getLogger(__name__)
+
+
++# A single path component: percent-decoded once and reduced to a basename, so it
++# contains no path separator and is not a ``.`` or ``..`` reference. The empty
++# string means "no component".
++PathComponent = NewType("PathComponent", str)
++
++
++def _to_path_component(name: str) -> PathComponent:
++    """Reduce ``name`` to a single path component, or ``""`` if it has none.
++
++    ``os.path.basename`` drops any directory part, drive letter, or separator;
++    a ``.``, ``..``, or empty result is not a component and becomes ``""``.
++    """
++    name = os.path.basename(name)
++    if name in ("", os.curdir, os.pardir):
++        return PathComponent("")
++
++    return PathComponent(name)
++
++
++def as_path_component(name: str) -> PathComponent:
++    """Like ``_to_path_component`` but reject the empty result.
++
++    Use where a file is about to be written, so a missing name is an error
++    rather than a silent fallback to the directory itself.
++    """
++    component = _to_path_component(name)
++    if not component:
++        raise ValueError(f"Unexpected file name derived from URL: {name!r}")
++
++    return component
++
++
++def join_within_directory(directory: str, component: PathComponent) -> str:
++    """Join a single path ``component`` onto ``directory``.
++
++    ``component`` is a :data:`PathComponent`, so by type it has no separator and
++    is not a ``.`` or ``..`` reference; the result can never escape ``directory``.
++    Requiring ``PathComponent`` rather than ``str`` lets the type checker enforce
++    at the call site that the name was reduced to a safe component beforehand.
++    """
++    return os.path.join(directory, component)
++
++
+ # Order matters, earlier hashes have a precedence over later hashes for what
+ # we will pick to use.
+ _SUPPORTED_HASHES = ("sha512", "sha384", "sha256", "sha224", "sha1", "md5")
+@@ -414,18 +458,13 @@ class Link:
+         return redact_auth_from_url(self.url)
+
+     @property
+-    def filename(self) -> str:
+-        path = self.path.rstrip("/")
+-        name = posixpath.basename(path)
+-        if not name:
+-            # Make sure we don't leak auth information if the netloc
+-            # includes a username and password.
+-            netloc, user_pass = split_auth_from_netloc(self.netloc)
+-            return netloc
+-
+-        name = urllib.parse.unquote(name)
+-        assert name, f"URL {self._url!r} produced no filename"
+-        return name
++    def filename(self) -> PathComponent:
++        name = _to_path_component(posixpath.basename(self.path.rstrip("/")))
++        if name:
++            return name
++
++        # No component in the path; fall back to the netloc, dropping any auth.
++        return _to_path_component(split_auth_from_netloc(self.netloc)[0])
+
+     @property
+     def file_path(self) -> str:
+diff --git a/pip/_internal/network/download.py b/pip/_internal/network/download.py
+index 9881cc2..16db065 100644
+--- a/pip/_internal/network/download.py
++++ b/pip/_internal/network/download.py
+@@ -20,7 +20,12 @@ from pip._vendor.urllib3.exceptions import ReadTimeoutError
+ from pip._internal.cli.progress_bars import BarType, get_download_progress_renderer
+ from pip._internal.exceptions import IncompleteDownloadError, NetworkConnectionError
+ from pip._internal.models.index import PyPI
+-from pip._internal.models.link import Link
++from pip._internal.models.link import (
++    Link,
++    PathComponent,
++    as_path_component,
++    join_within_directory,
++)
+ from pip._internal.network.cache import SafeFileCache, is_from_cache
+ from pip._internal.network.session import CacheControlAdapter, PipSession
+ from pip._internal.network.utils import HEADERS, raise_for_status, response_chunks
+@@ -117,11 +122,14 @@ def parse_content_disposition(content_disposition: str, default_filename: str) -
+     return filename or default_filename
+
+
+-def _get_http_response_filename(resp: Response, link: Link) -> str:
++def _get_http_response_filename(resp: Response, link: Link) -> PathComponent:
+     """Get an ideal filename from the given HTTP response, falling back to
+     the link filename if not provided.
++
++    The result is validated as a single path component, so it can be joined onto
++    a download directory without escaping it.
+     """
+-    filename = link.filename  # fallback
++    filename: str = link.filename  # fallback
+     # Have a look at the Content-Disposition header for a better guess
+     content_disposition = resp.headers.get("content-disposition")
+     if content_disposition:
+@@ -135,7 +143,7 @@ def _get_http_response_filename(resp: Response, link: Link) -> str:
+         ext = os.path.splitext(resp.url)[1]
+         if ext:
+             filename += ext
+-    return filename
++    return as_path_component(filename)
+
+
+ @dataclass
+@@ -189,7 +197,9 @@ class Downloader:
+         resp = self._http_get(link)
+         download_size = _get_http_response_size(resp)
+
+-        filepath = os.path.join(location, _get_http_response_filename(resp, link))
++        filepath = join_within_directory(
++            location, _get_http_response_filename(resp, link)
++        )
+         with open(filepath, "wb") as content_file:
+             download = _FileDownload(link, content_file, download_size)
+             self._process_response(download, resp)
+diff --git a/pip/_internal/operations/prepare.py b/pip/_internal/operations/prepare.py
+index a72e0e4..79828bb 100644
+--- a/pip/_internal/operations/prepare.py
++++ b/pip/_internal/operations/prepare.py
+@@ -29,7 +29,7 @@ from pip._internal.exceptions import (
+ from pip._internal.index.package_finder import PackageFinder
+ from pip._internal.metadata import BaseDistribution, get_metadata_distribution
+ from pip._internal.models.direct_url import ArchiveInfo
+-from pip._internal.models.link import Link
++from pip._internal.models.link import Link, join_within_directory
+ from pip._internal.models.wheel import Wheel
+ from pip._internal.network.download import Downloader
+ from pip._internal.network.lazy_wheel import (
+@@ -201,7 +201,7 @@ def _check_download_dir(
+     """Check download_dir for previously downloaded file with correct hash
+     If a correct file is found return its path else None
+     """
+-    download_path = os.path.join(download_dir, link.filename)
++    download_path = join_within_directory(download_dir, link.filename)
+
+     if not os.path.exists(download_path):
+         return None
+@@ -684,7 +684,7 @@ class RequirementPreparer:
+             # No distribution was downloaded for this requirement.
+             return
+
+-        download_location = os.path.join(self.download_dir, link.filename)
++        download_location = join_within_directory(self.download_dir, link.filename)
+         if not os.path.exists(download_location):
+             shutil.copy(req.local_file_path, download_location)
+             download_path = display_path(download_location)
+-- 
+2.45.4
+