[Secure-testing-team] Bug#863021: libxml2: CVE-2017-9048: another stack overflow in valid.c

[Salvatore Bonaccorso]

Source: libxml2
Version: 2.9.4+dfsg1-2.2
Severity: important
Tags: upstream security
Forwarded: https://bugzilla.gnome.org/show_bug.cgi?id=781701

Hi,

the following vulnerability was published for libxml2.

CVE-2017-9048[0]:
| libxml2 20904-GITv2.9.4-16-g0741801 is vulnerable to a stack-based
| buffer overflow. The function xmlSnprintfElementContent in valid.c is
| supposed to recursively dump the element content definition into a char
| buffer 'buf' of size 'size'. At the end of the routine, the function
| may strcat two more characters without checking whether the current
| strlen(buf) + 2 < size. This vulnerability causes programs that use
| libxml2, such as PHP, to crash.

The report at [1] mentions that this was reported upstream as [2], but
the upstream bug report is not yet opened. The posting at [1] contains
a patch which is not yet blessed upstream.

If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2017-9048
    https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-9048
[1] http://www.openwall.com/lists/oss-security/2017/05/15/1
[2] https://bugzilla.gnome.org/show_bug.cgi?id=781701

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore