diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py index 6624e04317ba28..56565405a70971 100644 --- a/Lib/urllib/request.py +++ b/Lib/urllib/request.py @@ -947,7 +947,7 @@ 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.
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