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.

• http://packetstormsecurity.com/files/153746/FreeBSD-Security-Advisory-FreeBSD-SA-19-12.telnet.html
• https://kb.juniper.net/JSA10947
• https://lists.debian.org/debian-lts-announce/2022/11/msg00033.html
• https://lists.debian.org/debian-lts-announce/2023/10/msg00013.html
• https://lists.debian.org/debian-lts-announce/2023/10/msg00013.html
• https://seclists.org/bugtraq/2019/Jul/45
• https://security.FreeBSD.org/advisories/FreeBSD-SA-19:12.telnet.asc
• https://www.exploit-db.com/exploits/45982
• http://packetstormsecurity.com/files/153746/FreeBSD-Security-Advisory-FreeBSD-SA-19-12.telnet.html
• https://kb.juniper.net/JSA10947
• https://lists.debian.org/debian-lts-announce/2022/11/msg00033.html
• https://lists.debian.org/debian-lts-announce/2023/10/msg00013.html
• https://lists.debian.org/debian-lts-announce/2023/10/msg00013.html
• https://seclists.org/bugtraq/2019/Jul/45
• https://security.FreeBSD.org/advisories/FreeBSD-SA-19:12.telnet.asc
• https://www.exploit-db.com/exploits/45982

• Debian » Debian Linux » Version: 10.0
  cpe:2.3:o:debian:debian_linux:10.0
• Juniper » Junos » Version: 12.3
  cpe:2.3:o:juniper:junos:12.3
• Juniper » Junos » Version: 12.3r12
  cpe:2.3:o:juniper:junos:12.3r12
• Juniper » Junos » Version: 12.3x48
  cpe:2.3:o:juniper:junos:12.3x48
• Juniper » Junos » Version: 14.1x53
  cpe:2.3:o:juniper:junos:14.1x53
• Juniper » Junos » Version: 15.1
  cpe:2.3:o:juniper:junos:15.1
• Juniper » Junos » Version: 15.1x49
  cpe:2.3:o:juniper:junos:15.1x49
• Juniper » Junos » Version: 15.1x53
  cpe:2.3:o:juniper:junos:15.1x53
• Juniper » Junos » Version: 16.1
  cpe:2.3:o:juniper:junos:16.1
• Juniper » Junos » Version: 16.2
  cpe:2.3:o:juniper:junos:16.2
• Juniper » Junos » Version: 17.1
  cpe:2.3:o:juniper:junos:17.1
• Juniper » Junos » Version: 17.2
  cpe:2.3:o:juniper:junos:17.2
• Juniper » Junos » Version: 17.3
  cpe:2.3:o:juniper:junos:17.3
• Juniper » Junos » Version: 17.4
  cpe:2.3:o:juniper:junos:17.4
• Juniper » Junos » Version: 18.1
  cpe:2.3:o:juniper:junos:18.1
• Juniper » Junos » Version: 18.2
  cpe:2.3:o:juniper:junos:18.2
• Juniper » Junos » Version: 18.2x75
  cpe:2.3:o:juniper:junos:18.2x75
• Juniper » Junos » Version: 18.3
  cpe:2.3:o:juniper:junos:18.3
• Juniper » Junos » Version: 18.4
  cpe:2.3:o:juniper:junos:18.4