microsoft · Yutong Song (RainieLLM) · Sep 19, 2026 · Sep 19, 2026
diff --git a/packages/markitdown/src/markitdown/converters/_bing_serp_converter.py b/packages/markitdown/src/markitdown/converters/_bing_serp_converter.py
@@ -1,7 +1,7 @@
 import re
 import base64
 import binascii
-from urllib.parse import parse_qs, urlparse
+from urllib.parse import ParseResult, parse_qs, urlparse
 from typing import Any, BinaryIO
 from bs4 import BeautifulSoup
 
@@ -20,6 +20,18 @@
 ]
 
 
+def _is_bing_redirect(parsed_href: ParseResult) -> bool:
+    """Return True only for Bing's own `/ck/a` redirect links.
+
+    A normal result may use `u=` for its own purpose. So the base64 payload is
+    decoded only when the link is one that Bing wrapped.
+    """
+    host = (parsed_href.netloc or "").lower()
+    if host != "bing.com" and not host.endswith(".bing.com"):
+        return False
+    return parsed_href.path == "/ck/a"
+
+
 class BingSerpConverter(DocumentConverter):
     """
     Handle Bing results pages (only the organic search results).
@@ -87,6 +99,12 @@ def convert(
             # Rewrite redirect urls
             for a in result.find_all("a", href=True):
                 parsed_href = urlparse(a["href"])
+
+                # Keep normal result URLs as they are. Only Bing's redirect
+                # links carry the base64 `u` payload.
+                if not _is_bing_redirect(parsed_href):
+                    continue
+
                 qs = parse_qs(parsed_href.query)
 
                 # The destination is contained in the u parameter,

diff --git a/packages/markitdown/tests/test_bing_serp_converter.py b/packages/markitdown/tests/test_bing_serp_converter.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python3 -m pytest
+"""A result URL that uses `u=` for its own purpose must survive conversion.
+
+Bing puts each search result behind a `/ck/a` redirect link. The real
+destination sits in a base64 `u` query parameter. The converter decodes that
+parameter, but it did so for every link that has `u=`. A normal result that
+uses `u=` for its own purpose was therefore rewritten into garbage.
+"""
+
+import io
+
+from markitdown import MarkItDown, StreamInfo
+
+SERP_URL = "https://www.bing.com/search?q=python"
+
+REDIRECT_TARGET = "https://docs.python.org/3/"
+REDIRECT_HREF = (
+    "https://www.bing.com/ck/a?!&amp;&amp;p=xyz"
+    "&amp;u=a1aHR0cHM6Ly9kb2NzLnB5dGhvbi5vcmcvMy8="
+)
+
+NORMAL_HREF = "https://example.com/profile?u=abcdef"
+
+LOOKALIKE_HREF = "https://not-bing.com/ck/a?u=a1aHR0cHM6Ly9kb2NzLnB5dGhvbi5vcmcvMy8="
+
+LOOKALIKE_PATH_HREF = (
+    "https://www.bing.com/ck/abc?u=a1aHR0cHM6Ly9kb2NzLnB5dGhvbi5vcmcvMy8="
+)
+
+
+def _serp(*hrefs: str) -> io.BytesIO:
+    items = "".join(
+        '<li class="b_algo"><h2><a href="%s">Result %d</a></h2><p>Snippet %d.</p></li>'
+        % (href, i, i)
+        for i, href in enumerate(hrefs, start=1)
+    )
+    html = (
+        "<html><head><title>python - Search</title></head><body>"
+        '<ol id="b_results">%s</ol></body></html>' % items
+    )
+    return io.BytesIO(html.encode("utf-8"))
+
+
+def _convert(*hrefs: str) -> str:
+    return (
+        MarkItDown()
+        .convert_stream(
+            _serp(*hrefs),
+            stream_info=StreamInfo(
+                url=SERP_URL,
+                mimetype="text/html",
+                extension=".html",
+                charset="utf-8",
+            ),
+        )
+        .markdown
+    )
+
+
+def test_bing_redirect_is_decoded_to_its_destination() -> None:
+    markdown = _convert(REDIRECT_HREF)
+
+    assert "](%s)" % REDIRECT_TARGET in markdown
+    assert "ck/a" not in markdown
+
+
+def test_normal_url_keeps_its_own_u_parameter() -> None:
+    markdown = _convert(NORMAL_HREF)
+
+    assert "](%s)" % NORMAL_HREF in markdown
+
+
+def test_normal_url_survives_next_to_a_redirect() -> None:
+    markdown = _convert(REDIRECT_HREF, NORMAL_HREF)
+
+    assert "](%s)" % REDIRECT_TARGET in markdown
+    assert "](%s)" % NORMAL_HREF in markdown
+
+
+def test_lookalike_host_is_not_treated_as_a_bing_redirect() -> None:
+    markdown = _convert(LOOKALIKE_HREF)
+
+    assert "](%s)" % LOOKALIKE_HREF in markdown
+
+
+def test_lookalike_path_is_not_treated_as_a_bing_redirect() -> None:
+    markdown = _convert(LOOKALIKE_PATH_HREF)
+
+    assert "](%s)" % LOOKALIKE_PATH_HREF in markdown