Use-after-free in Linux Kernel modify_ldt()

1) Use-after-free

EUVDB-ID: #VU19110

Risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2019-13233

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error within the arch/x86/lib/insn-eval.c file due to a race condition between modify_ldt() and a #BR exception for an MPX bounds violation when accessing LDT entry. A local user can create a specially crafted application and escalate privileges on the system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Linux kernel: 5.1.1 - 5.1.8

CPE2.3

• cpe:2.3:o:linux_foundation:linux_kernel:5.1.1:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:5.1.2:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:5.1.3:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:5.1.4:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:5.1.5:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:5.1.6:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:5.1.7:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:5.1.8:*:*:*:*:*:*:*

External links

https://bugs.chromium.org/p/project-zero/issues/detail?id=1879
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.1.9
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=de9f869616dd95e95c00bdd6b0fcd3421e8a4323
https://github.com/torvalds/linux/commit/de9f869616dd95e95c00bdd6b0fcd3421e8a4323

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.