CVE-2012-4562: Buffer Overflow
First published: Tue Oct 30 2012(Updated: )
Florian Weimer of the Red Hat Product Security Team reported many instances of overflow checks in libssh's buffer.c that were incorrect: if ((buffer->pos + hostlen) > buffer->used) { This should probably be: if (hostlen > buffer->used - buffer->pos) { It seems this could be used to trigger a large memory allocation which is immediately freed, so this is mostly harmless (not exploitable for code execution or denial of service). A similar problem occurs in buffer_add_data(): if (buffer->allocated < (buffer->used + len)) { len should stand on its own. Likewise in buffer_prepend_data(): if (buffer->allocated < (buffer->used - buffer->pos + len)) { And buffer_pass_bytes(), buffer_pass_bytes_end(), buffer_get_mpint(): if(buffer->used < buffer->pos+len) if(buffer->used < buffer->pos + len) if ((buffer->pos + len) > buffer->used) { While it is not certain that any of these are actually be exploitable, the checks are incorrect and need to be fixed.
Credit: secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Libssh Libssh | <=0.5.2 | |
| Libssh Libssh | =0.4.7 | |
| Libssh Libssh | =0.4.8 | |
| Libssh Libssh | =0.5.0 | |
| Libssh Libssh | =0.5.0-rc1 | |
| Libssh Libssh | =0.5.1 | |
| redhat/libssh | <0.5.3 | 0.5.3 |
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Reference Links
- http://lists.fedoraproject.org/pipermail/package-announce/2012-November/093313.html
- http://lists.fedoraproject.org/pipermail/package-announce/2012-November/093474.html
- http://lists.opensuse.org/opensuse-security-announce/2012-11/msg00015.html
- http://lists.opensuse.org/opensuse-security-announce/2012-12/msg00002.html
- http://lists.opensuse.org/opensuse-updates/2012-12/msg00016.html
- http://lists.opensuse.org/opensuse-updates/2013-01/msg00021.html
- http://www.debian.org/security/2012/dsa-2577
- http://www.libssh.org/2012/11/20/libssh-0-5-3-security-release/
- http://www.mandriva.com/security/advisories?name=MDVSA-2012:175
- http://www.openwall.com/lists/oss-security/2012/11/20/3
- http://www.securityfocus.com/bid/56604
- http://www.ubuntu.com/usn/USN-1640-1
- https://bugzilla.redhat.com/show_bug.cgi?id=871620
- https://exchange.xforce.ibmcloud.com/vulnerabilities/80221
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645002&action=diff
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645002&action=edit
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645003&action=diff
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645003&action=edit
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645004&action=diff
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645004&action=edit
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645018&action=diff
- https://bugzilla.redhat.com/show_bug.cgi/attachment.cgi?id=645018&action=edit
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=878521
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- version/libssh libssh/0.5.0-rc1
- version/libssh libssh/0.5.1
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