CVE-2019-0053 Junos OS: Insufficient validation of environment variables in telnet client may lead to stack-based buffer overflow

High 7.8 Published 11 Jul 2019 Updated 16 Sep 2024

Stack-based buffer overflow in Junos OS telnet client allows bypassing veriexec restrictions, potentially leading to privilege escalation or code execution.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2019-0053?

CVE-2019-0053 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 11 Jul 2019. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Insufficient validation of environment variables in the telnet client supplied in Junos OS can lead to stack-based buffer overflows, which can be exploited to bypass veriexec restrictions on Junos OS. A stack-based overflow is present in the handling of environment variables when connecting via the telnet client to remote telnet servers. This issue only affects the telnet client — accessible from the CLI or shell — in Junos OS. Inbound telnet services are not affected by this issue. This issue affects: Juniper Networks Junos OS: 12.3 versions prior to 12.3R12-S13; 12.3X48 versions prior to 12.3X48-D80; 14.1X53 versions prior to 14.1X53-D130, 14.1X53-D49; 15.1 versions prior to 15.1F6-S12, 15.1R7-S4; 15.1X49 versions prior to 15.1X49-D170; 15.1X53 versions prior to 15.1X53-D237, 15.1X53-D496, 15.1X53-D591, 15.1X53-D69; 16.1 versions prior to 16.1R3-S11, 16.1R7-S4; 16.2 versions prior to 16.2R2-S9; 17.1 versions prior to 17.1R3; 17.2 versions prior to 17.2R1-S8, 17.2R2-S7, 17.2R3-S1; 17.3 versions prior to 17.3R3-S4; 17.4 versions prior to 17.4R1-S6, 17.4R2-S3, 17.4R3; 18.1 versions prior to 18.1R2-S4, 18.1R3-S3; 18.2 versions prior to 18.2R1-S5, 18.2R2-S2, 18.2R3; 18.2X75 versions prior to 18.2X75-D40; 18.3 versions prior to 18.3R1-S3, 18.3R2; 18.4 versions prior to 18.4R1-S2, 18.4R2.

Weakness: CWE-787, CWE-121

Which versions are affected by CVE-2019-0053?

It affects 2 products.

Products include Debian Debian Linux, Juniper Junos.

How do I fix CVE-2019-0053?

Upgrade to a fixed version.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2019-0053 being exploited?

There is no known exploitation of CVE-2019-0053 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

All Debian Debian Linux vulnerabilities

Sources

Also known as DEBIAN-CVE-2019-0053, GHSA-4vvc-hp8x-p32m, UBUNTU-CVE-2019-0053.