<s>
Cloudbleed	B-Error_Name
was	O
a	O
Cloudflare	B-Application
buffer	B-General_Concept
overflow	I-General_Concept
disclosed	O
by	O
Project	B-Application
Zero	I-Application
on	O
February	O
17	O
,	O
2017	O
.	O
</s>
<s>
Cloudflare	B-Application
's	O
code	O
disclosed	O
the	O
contents	O
of	O
memory	O
that	O
contained	O
the	O
private	O
information	O
of	O
other	O
customers	O
,	O
such	O
as	O
HTTP	B-Application
cookies	I-Application
,	O
authentication	O
tokens	O
,	O
HTTP	B-Protocol
POST	I-Protocol
bodies	O
,	O
and	O
other	O
sensitive	O
data	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
data	O
from	O
Cloudflare	B-Application
customers	O
was	O
leaked	O
to	O
all	O
other	O
Cloudflare	B-Application
customers	O
that	O
had	O
access	O
to	O
server	O
memory	O
.	O
</s>
<s>
This	O
occurred	O
,	O
according	O
to	O
numbers	O
provided	O
by	O
Cloudflare	B-Application
at	O
the	O
time	O
,	O
more	O
than	O
18,000,000	O
times	O
before	O
the	O
problem	O
was	O
corrected	O
.	O
</s>
<s>
Some	O
of	O
the	O
leaked	O
data	O
was	O
cached	B-General_Concept
by	O
search	B-Application
engines	I-Application
.	O
</s>
<s>
The	O
discovery	O
was	O
reported	O
by	O
Google	O
's	O
Project	B-Application
Zero	I-Application
team	O
.	O
</s>
<s>
Tavis	O
Ormandy	O
posted	O
the	O
issue	O
on	O
his	O
team	O
's	O
issue	O
tracker	O
and	O
said	O
that	O
he	O
informed	O
Cloudflare	B-Application
of	O
the	O
problem	O
on	O
February	O
17	O
.	O
</s>
<s>
In	O
his	O
own	O
proof-of-concept	O
attack	O
he	O
got	O
a	O
Cloudflare	B-Application
server	O
to	O
return	O
"	O
private	O
messages	O
from	O
major	O
dating	O
sites	O
,	O
full	O
messages	O
from	O
a	O
well-known	O
chat	O
service	O
,	O
online	O
password	O
manager	O
data	O
,	O
frames	O
from	O
adult	O
video	O
sites	O
,	O
hotel	O
bookings	O
.	O
</s>
<s>
We	O
're	O
talking	O
full	O
https	O
requests	O
,	O
client	O
IP	O
addresses	O
,	O
full	O
responses	O
,	O
cookies	B-Application
,	O
passwords	O
,	O
keys	O
,	O
data	O
,	O
everything.	O
"	O
</s>
<s>
In	O
its	O
effects	O
,	O
Cloudbleed	B-Error_Name
is	O
comparable	O
to	O
the	O
2014	O
Heartbleed	B-Error_Name
bug	I-Error_Name
,	O
in	O
that	O
it	O
allowed	O
unauthorized	O
third	O
parties	O
to	O
access	O
data	O
in	O
the	O
memory	O
of	O
programs	O
running	O
on	O
web	O
servers	O
,	O
including	O
data	O
which	O
had	O
been	O
shielded	O
while	O
in	O
transit	O
by	O
TLS	B-Protocol
.	O
</s>
<s>
Cloudbleed	B-Error_Name
also	O
likely	O
impacted	O
as	O
many	O
users	O
as	O
Heartbleed	B-Error_Name
since	O
it	O
affected	O
a	O
content	O
delivery	O
network	O
serving	O
nearly	O
two	O
million	O
websites	O
.	O
</s>
<s>
Tavis	O
Ormandy	O
,	O
first	O
to	O
discover	O
the	O
vulnerability	O
,	O
immediately	O
drew	O
a	O
comparison	O
to	O
Heartbleed	B-Error_Name
,	O
saying	O
"	O
it	O
took	O
every	O
ounce	O
of	O
strength	O
not	O
to	O
call	O
this	O
issue	O
'	O
cloudbleed	B-Error_Name
 '	O
"	O
in	O
his	O
report	O
.	O
</s>
<s>
On	O
Thursday	O
,	O
February	O
23	O
,	O
2017	O
,	O
Cloudflare	B-Application
wrote	O
a	O
post	O
noting	O
that:The	O
bug	O
was	O
serious	O
because	O
the	O
leaked	O
memory	O
could	O
contain	O
private	O
information	O
and	O
because	O
it	O
had	O
been	O
cached	B-General_Concept
by	O
search	B-Application
engines	I-Application
.	O
</s>
<s>
The	O
greatest	O
period	O
of	O
impact	O
was	O
from	O
February	O
13	O
and	O
February	O
18	O
with	O
around	O
1	O
in	O
every	O
3,300,000	O
HTTP	O
requests	O
through	O
Cloudflare	B-Application
potentially	O
resulting	O
in	O
memory	O
leakage	O
(	O
that	O
’s	O
about	O
0.00003	O
%	O
of	O
requests	O
)	O
.Cloudflare	O
acknowledged	O
that	O
the	O
memory	O
could	O
have	O
leaked	O
as	O
early	O
as	O
September	O
22	O
,	O
2016	O
.	O
</s>
<s>
It	O
turned	O
out	O
that	O
the	O
underlying	O
bug	O
that	O
caused	O
the	O
memory	O
leak	O
had	O
been	O
present	O
in	O
our	O
Ragel-based	O
parser	B-Language
for	O
many	O
years	O
but	O
no	O
memory	O
was	O
leaked	O
because	O
of	O
the	O
way	O
the	O
internal	O
NGINX	B-Operating_System
buffers	O
were	O
used	O
.	O
</s>
<s>
John	O
Graham-Cumming	O
,	O
Cloudflare	B-Application
CTO	O
,	O
noted	O
that	O
Cloudflare	B-Application
clients	O
,	O
such	O
as	O
Uber	O
and	O
OkCupid	O
,	O
were	O
n't	O
directly	O
informed	O
of	O
the	O
leaks	O
due	O
to	O
the	O
security	O
risks	O
involved	O
in	O
the	O
situation	O
.	O
</s>
<s>
“	O
There	O
was	O
no	O
backdoor	O
communication	O
outside	O
of	O
Cloudflare	B-Application
—	O
only	O
with	O
Google	O
and	O
other	O
search	B-Application
engines	I-Application
,	O
”	O
he	O
said	O
.	O
</s>
<s>
Tavis	O
Ormandy	O
initially	O
stated	O
that	O
he	O
was	O
"	O
really	O
impressed	O
with	O
Cloudflare	B-Application
's	O
quick	O
response	O
,	O
and	O
how	O
dedicated	O
they	O
are	O
to	O
cleaning	O
up	O
from	O
this	O
unfortunate	O
issue.	O
"	O
</s>
<s>
However	O
,	O
when	O
Ormandy	O
pressed	O
Cloudflare	B-Application
for	O
additional	O
information	O
,	O
"	O
They	O
gave	O
several	O
excuses	O
that	O
did	O
n't	O
make	O
sense	O
,	O
"	O
before	O
sending	O
a	O
draft	O
that	O
"	O
severely	O
downplays	O
the	O
risk	O
to	O
customers.	O
"	O
</s>
<s>
OKCupid	O
CEO	O
Elie	O
Seidman	O
said	O
:	O
"	O
CloudFlare	B-Application
alerted	O
us	O
last	O
night	O
of	O
their	O
bug	O
and	O
we	O
've	O
been	O
looking	O
into	O
its	O
impact	O
on	O
OkCupid	O
members	O
.	O
</s>
<s>
Many	O
major	O
news	O
outlets	O
advised	O
users	O
of	O
sites	O
hosted	O
by	O
Cloudflare	B-Application
to	O
change	O
their	O
passwords	O
,	O
as	O
even	O
accounts	O
protected	O
by	O
multi-factor	O
authentication	O
could	O
be	O
at	O
risk	O
.	O
</s>
