An Improper Check for Unusual or Exceptional Conditions vulnerability in the SIP ALG of Juniper Networks Junos OS on SRX Series and MX Series allows an unauthenticated network-based attacker to cause an integrity impact in connected networks.

If the SIP ALG is configured and a device receives a specifically malformed SIP packet, the device prevents this packet from being forwarded, but any subsequently received retransmissions of the same packet are forwarded as if they were valid.

This issue affects Juniper Networks Junos OS on SRX Series and MX Series:

• 20.4 versions prior to 20.4R3-S5;
• 21.1 versions prior to 21.1R3-S4;
• 21.2 versions prior to 21.2R3-S4;
• 21.3 versions prior to 21.3R3-S3;
• 21.4 versions prior to 21.4R3-S2;
• 22.1 versions prior to 22.1R2-S2, 22.1R3;
• 22.2 versions prior to 22.2R2-S1, 22.2R3;
• 22.3 versions prior to 22.3R1-S2, 22.3R2.

This issue doesn't not affected releases prior to 20.4R1.