From 1fa7f6ecaf15af550fb78a841b7c3d8f0b99093c 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 4f42919b09eaee..16b7e1c50985d1 100644 --- a/Lib/urllib/request.py +++ b/Lib/urllib/request.py @@ -946,7 +946,7 @@ 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.