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Bug 156476 - app-crypt/gnupg 1.4 and 2.0 buffer overflow (CVE-2006-6169)
Summary: app-crypt/gnupg 1.4 and 2.0 buffer overflow (CVE-2006-6169)
Alias: None
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Other
: High normal (vote)
Assignee: Gentoo Security
Whiteboard: B2 [glsa]
Depends on:
Reported: 2006-11-27 21:58 UTC by Rajiv Aaron Manglani (RETIRED)
Modified: 2006-12-10 05:38 UTC (History)
1 user (show)

See Also:
Package list:
Runtime testing required: ---


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Description Rajiv Aaron Manglani (RETIRED) gentoo-dev 2006-11-27 21:58:24 UTC
	Subject: 	GnuPG 1.4 and 2.0 buffer overflow
	Date: 	November 27, 2006 12:13:02 PM EST

            GnuPG 1.4 and 2.0 buffer overflow


While fixing a bug reported by Hugh Warrington, a buffer overflow has
been identified in all released GnuPG versions.  The current versions
1.4.5 and 2.0.0 are affected.  A small patch is provided.

Please do not send private mail in response to this message.  The
mailing list gnupg-devel is the best place to discuss this problem
(please subscribe first so you don't need moderator approval [1]).


When running GnuPG interactively, special crafted messages may be used
to crash gpg or gpg2.  Running gpg in batch mode, as done by all
software using gpg as a backend (e.g. mailers), is not affected by
this bug.

Exploiting this overflow seems to be possible.

gpg-agent, gpgsm, gpgv or other tools from the GnuPG suite are not


Apply the following patch to GnuPG.  It should apply cleanly to
current versions (1.4.5 as well as 2.0.0) but might also work for
older versions. 

2006-11-27  Werner Koch  <>

	* openfile.c (ask_outfile_name): Fixed buffer overflow occurring
	if make_printable_string returns a longer string.  Fixes bug 728.

--- g10/openfile.c      (revision 4348)
+++ g10/openfile.c      (working copy)
@@ -144,8 +144,8 @@

     s = _("Enter new filename");

-    n = strlen(s) + namelen + 10;
     defname = name && namelen? make_printable_string( name, namelen, 0): NULL;
+    n = strlen(s) + (defname?strlen (defname):0) + 10;
     prompt = xmalloc(n);
     if( defname )
        sprintf(prompt, "%s [%s]: ", s, defname );


The code in question has been introduced on July 1, 1999 and is a
pretty obvious bug.  make_printable_string is supposed to replace
possible dangerous characters from a prompt and returns a malloced
string.  Thus this string may be longer than the orginal one; the
buffer for the prompt has only be allocated at the size of the original
string - oops.  Note, that using snprintf would not have helped in
this case.  How I wish C-90 had introduced asprintf or at least it
would be available on more platforms.

The original bug report is at .

[1] See .

Werner Koch                                      <>
The GnuPG Experts                      
Join the Fellowship and protect your Freedom!
Comment 1 Robin Johnson archtester Gentoo Infrastructure gentoo-dev Security 2006-11-27 22:10:57 UTC
and if you read the rest of the announcements on the relevant mailing lists, 1.4.6/2.0.1 will be out in a day or two to resolve this.
Comment 2 Tavis Ormandy (RETIRED) gentoo-dev 2006-11-28 01:38:26 UTC
doesnt seem like a security issue, unless you can get someone to type in lots of (partially binary) characters.

Can anyone think of an attack using this bug?
Comment 3 Stefan Cornelius (RETIRED) gentoo-dev 2006-11-28 05:37:17 UTC
where exactly do you have to type something? As I currently understand it, this can be triggered by interactively runnung gpg on a malicious file (like the one the reported attached to the upstream bug) - but I had no deep look here, since the vendor came out with this (and well, I seriously hope that they know what they are doing).
Comment 4 Tavis Ormandy (RETIRED) gentoo-dev 2006-11-28 07:18:56 UTC
Ahh, I see what you mean, I hadnt read the bug.

Yes, this looks like it would be a problem then, ignore my last comment.
Comment 5 Robin Johnson archtester Gentoo Infrastructure gentoo-dev Security 2006-11-30 12:38:22 UTC
upstream has 2.0.1 out, but not 1.4.6 yet.
Comment 6 Matthias Geerdsen (RETIRED) gentoo-dev 2006-12-05 12:34:03 UTC
has not been fully wrangled so far... 
rating B2...

just to fill this comment field...
Comment 7 Rajiv Aaron Manglani (RETIRED) gentoo-dev 2006-12-06 12:10:18 UTC
gnupg 1.4.6 is now available at 
Comment 8 Alon Bar-Lev (RETIRED) gentoo-dev 2006-12-06 13:15:23 UTC
Comment 9 Sune Kloppenborg Jeppesen gentoo-dev 2006-12-07 03:31:24 UTC
Please don't close Security bugs.

This one is ready for GLSA.
Comment 10 Raphael Marichez (Falco) (RETIRED) gentoo-dev 2006-12-10 05:38:55 UTC
GLSA 200612-03