From 760e4340789a009733d87a6b3cac8d9cc16cc0bb Mon Sep 17 00:00:00 2001 From: Yeting Li Date: Wed, 7 Apr 2021 19:27:41 +0800 Subject: [PATCH] bpo-43075: Fix ReDoS in urllib AbstractBasicAuthHandler (GH-24391) Fix Regular Expression Denial of Service (ReDoS) vulnerability in urllib.request.AbstractBasicAuthHandler. The ReDoS-vulnerable regex has quadratic worst-case complexity and it allows cause a denial of service when identifying crafted invalid RFCs. This ReDoS issue is on the client side and needs remote attackers to control the HTTP server. (cherry picked from commit 7215d1ae25525c92b026166f9d5cac85fb1defe1) Co-authored-by: Yeting Li --- Lib/urllib/request.py | 2 +- .../next/Security/2021-01-31-05-28-14.bpo-43075.DoAXqO.rst | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/Security/2021-01-31-05-28-14.bpo-43075.DoAXqO.rst diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py index 57d991465a5b0c..af3fb9ca54a0b4 100644 --- a/Lib/urllib/request.py +++ b/Lib/urllib/request.py @@ -943,7 +943,7 @@ class AbstractBasicAuthHandler: # (single quotes are a violation of the RFC, but appear in the wild) rx = re.compile('(?:^|,)' # start of the string or ',' '[ \t]*' # optional whitespaces - '([^ \t]+)' # scheme like "Basic" + '([^ \t,]+)' # scheme like "Basic" '[ \t]+' # mandatory whitespaces # realm=xxx # realm='xxx' diff --git a/Misc/NEWS.d/next/Security/2021-01-31-05-28-14.bpo-43075.DoAXqO.rst b/Misc/NEWS.d/next/Security/2021-01-31-05-28-14.bpo-43075.DoAXqO.rst new file mode 100644 index 00000000000000..1c9f727e965fb8 --- /dev/null +++ b/Misc/NEWS.d/next/Security/2021-01-31-05-28-14.bpo-43075.DoAXqO.rst @@ -0,0 +1 @@ +Fix Regular Expression Denial of Service (ReDoS) vulnerability in :class:`urllib.request.AbstractBasicAuthHandler`. The ReDoS-vulnerable regex has quadratic worst-case complexity and it allows cause a denial of service when identifying crafted invalid RFCs. This ReDoS issue is on the client side and needs remote attackers to control the HTTP server.