SB2017102909 - Gentoo update for X.Org Server

Description

This security bulletin contains information about 4 secuirty vulnerabilities.

1) Input validation error (CVE-ID: CVE-2013-6424)

The vulnerability allows a remote non-authenticated attacker to perform service disruption.

Integer underflow in the xTrapezoidValid macro in render/picture.h in X.Org allows context-dependent attackers to cause a denial of service (crash) via a negative bottom value.

2) Improper Privilege Management (CVE-ID: CVE-2017-13721)

The vulnerability allows a local authenticated user to perform a denial of service (DoS) attack.

In X.Org Server (aka xserver and xorg-server) before 1.19.4, an attacker authenticated to an X server with the X shared memory extension enabled can cause aborts of the X server or replace shared memory segments of other X clients in the same session.

3) Buffer overflow (CVE-ID: CVE-2017-13723)

The vulnerability allows a local authenticated user to execute arbitrary code.

In X.Org Server (aka xserver and xorg-server) before 1.19.4, a local attacker authenticated to the X server could overflow a global buffer, causing crashes of the X server or potentially other problems by injecting large or malformed XKB related atoms and accessing them via xkbcomp.

4) Information disclosure (CVE-ID: CVE-2017-2624)

The vulnerability allows a local authenticated user to execute arbitrary code.

It was found that xorg-x11-server before 1.19.0 including uses memcmp() to check the received MIT cookie against a series of valid cookies. If the cookie is correct, it is allowed to attach to the Xorg session. Since most memcmp() implementations return after an invalid byte is seen, this causes a time difference between a valid and invalid byte, which could allow an efficient brute force attack.

Remediation

Install update from vendor's website.

References

• https://security.gentoo.org/
• https://security.gentoo.org/glsa/201710-30