user: Describe the vulnerability: Provide detailed information about the vulnerability for CVE-2018-0049.

assistant: A NULL Pointer Dereference vulnerability in Juniper Networks Junos OS allows an attacker to cause the Junos OS kernel to crash. Continued receipt of this specifically crafted malicious MPLS packet will cause a sustained Denial of Service condition. This issue require it to be received on an interface configured to receive this type of traffic. Affected releases are Juniper Networks Junos OS: 12.1X46 versions above and including 12.1X46-D76 prior to 12.1X46-D81 on SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 12.3R12-S10; 12.3X48 versions above and including 12.3X48-D66 prior to 12.3X48-D75 on SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 14.1X53-D47 on EX2200/VC, EX3200, EX3300/VC, EX4200, EX4300, EX4550/VC, EX4600, EX6200, EX8200/VC (XRE), QFX3500, QFX3600, QFX5100; 14.1X53 versions above and including 14.1X53-D115 prior to 14.1X53-D130 on QFabric System; 15.1 versions above and including 15.1F6-S10; 15.1R4-S9; 15.1R6-S6; 15.1 versions above and including 15.1R7 prior to 15.1R7-S2; 15.1X49 versions above and including 15.1X49-D131 prior to 15.1X49-D150 on SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 15.1X53 versions above 15.1X53-D233 prior to 15.1X53-D235 on QFX5200/QFX5110; 15.1X53 versions up to and including 15.1X53-D471 prior to 15.1X53-D590 on NFX150, NFX250; 15.1X53-D67 on QFX10000 Series; 15.1X53-D59 on EX2300/EX3400; 16.1 versions above and including 16.1R3-S8; 16.1 versions above and including 16.1R4-S9 prior to 16.1R4-S12; 16.1 versions above and including 16.1R5-S4; 16.1 versions above and including 16.1R6-S3 prior to 16.1R6-S6; 16.1 versions above and including 16.1R7 prior to 16.1R7-S2; 16.2 versions above and including 16.2R1-S6; 16.2 versions above and including 16.2R2-S5 prior to 16.2R2-S7; 17.1R1-S7; 17.1 versions above and including 17.1R2-S7 prior to 17.1R2-S9; 17.2R1-S6; 17.2 versions above and including 17.2R2-S4 prior to 17.2R2-S6; 17.2X75 versions above and including 17.2X75-D100 prior to X17.2X75-D101, 17.2X75-D110; 17.3 versions above and including 17.3R1-S4 on All non-SRX Series and SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 17.3 versions above and including 17.3R2-S2 prior to 17.3R2-S4 on All non-SRX Series and SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 17.3R3 on All non-SRX Series and SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 17.4 versions above and including 17.4R1-S3 prior to 17.4R1-S5 on All non-SRX Series and SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 17.4R2 on All non-SRX Series and SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 18.1 versions above and including 18.1R2 prior to 18.1R2-S3, 18.1R3 on All non-SRX Series and SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 18.2 versions above and including 18.2R1 prior to 18.2R1-S2, 18.2R1-S3, 18.2R2 on All non-SRX Series and SRX100, SRX110, SRX210, SRX220, SRX240m, SRX550m SRX650, SRX300, SRX320, SRX340, SRX345, SRX1500, SRX4100, SRX4200, SRX4600 and vSRX; 18.2X75 versions above and including 18.2X75-D5 prior to 18.2X75-D20.