GnuPG: ElGamal signing keys compromised and format string vulnerability
Gentoo Linux Security Advisory
||GLSA 200312-05 / GnuPG
||December 12, 2003
||December 12, 2003: 01
All supported architectures
A bug in GnuPG allows ElGamal signing keys to be compromised, and a format
string bug in the gpgkeys_hkp utility may allow arbitrary code execution.
GnuPG is a popular open source signing and encryption tool.
Two flaws have been found in GnuPG 1.2.3.
First, ElGamal signing keys can be compromised. These keys are not commonly
used, but this is "a significant security failure which can lead to a
compromise of almost all ElGamal keys used for signing. Note that this is a
real world vulnerability which will reveal your private key within a few
Second, there is a format string flaw in the 'gpgkeys_hkp' utility which
"would allow a malicious keyserver in the worst case to execute an arbitrary
code on the user's machine."
If you have used ElGamal keys for signing your private key can be
compromised, and a malicious keyserver could remotely execute arbitrary code
with the permissions of the user running gpgkeys_hkp.
There is no known workaround at this time.
All users who have created ElGamal signing keys should immediately revoke
them. In addition, all Gentoo Linux machines with gnupg installed should be
updated to use gnupg-1.2.3-r5 or higher:
Code Listing 3.1: Resolution
# emerge sync
# emerge -pv '>=app-crypt/gnupg-1.2.3-r5'
# emerge '>=app-crypt/gnupg-1.2.3-r5'
# emerge clean