1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
$NetBSD: patch-Lib_mailcap.py,v 1.1 2022/08/11 01:32:50 gutteridge Exp $
Fix CVE-2015-20107: Make mailcap refuse to match unsafe filenames/types/params
Via Fedora:
https://src.fedoraproject.org/rpms/python2.7/raw/a9b12e85bd4d3280e07bc3bfa72a9f2b674cb4ff/f/00382-cve-2015-20107.patch
--- Lib/mailcap.py.orig 2020-04-19 21:13:39.000000000 +0000
+++ Lib/mailcap.py
@@ -1,9 +1,18 @@
"""Mailcap file handling. See RFC 1524."""
import os
+import warnings
+import re
__all__ = ["getcaps","findmatch"]
+
+_find_unsafe = re.compile(r'[^\xa1-\xff\w@+=:,./-]').search
+
+class UnsafeMailcapInput(Warning):
+ """Warning raised when refusing unsafe input"""
+
+
# Part 1: top-level interface.
def getcaps():
@@ -144,15 +153,22 @@ def findmatch(caps, MIMEtype, key='view'
entry to use.
"""
+ if _find_unsafe(filename):
+ msg = "Refusing to use mailcap with filename %r. Use a safe temporary filename." % (filename,)
+ warnings.warn(msg, UnsafeMailcapInput)
+ return None, None
entries = lookup(caps, MIMEtype, key)
# XXX This code should somehow check for the needsterminal flag.
for e in entries:
if 'test' in e:
test = subst(e['test'], filename, plist)
+ if test is None:
+ continue
if test and os.system(test) != 0:
continue
command = subst(e[key], MIMEtype, filename, plist)
- return command, e
+ if command is not None:
+ return command, e
return None, None
def lookup(caps, MIMEtype, key=None):
@@ -184,6 +200,10 @@ def subst(field, MIMEtype, filename, pli
elif c == 's':
res = res + filename
elif c == 't':
+ if _find_unsafe(MIMEtype):
+ msg = "Refusing to substitute MIME type %r into a shell command." % (MIMEtype,)
+ warnings.warn(msg, UnsafeMailcapInput)
+ return None
res = res + MIMEtype
elif c == '{':
start = i
@@ -191,7 +211,12 @@ def subst(field, MIMEtype, filename, pli
i = i+1
name = field[start:i]
i = i+1
- res = res + findparam(name, plist)
+ param = findparam(name, plist)
+ if _find_unsafe(param):
+ msg = "Refusing to substitute parameter %r (%s) into a shell command" % (param, name)
+ warnings.warn(msg, UnsafeMailcapInput)
+ return None
+ res = res + param
# XXX To do:
# %n == number of parts if type is multipart/*
# %F == list of alternating type and filename for parts
|
