An Improper Locking vulnerability in the SIP ALG of Juniper Networks Junos OS on MX Series with MS-MPC or MS-MIC card and SRX Series allows an unauthenticated, network-based attacker to cause a flow processing daemon (flowd) crash and thereby a Denial of Service (DoS). Continued receipt of these specific packets will cause a sustained Denial of Service condition. This issue occurs when SIP ALG is enabled and specific SIP messages are processed simultaneously. This issue affects: Juniper Networks Junos OS on MX Series and SRX Series 20.4 versions prior to 20.4R3-S4; 21.1 versions prior to 21.1R3-S3; 21.2 versions prior to 21.2R3-S2; 21.3 versions prior to 21.3R3; 21.4 versions prior to 21.4R3; 22.1 versions prior to 22.1R2. This issue does not affect Juniper Networks Junos OS versions prior to 20.4R1 on MX Series, or SRX Series.
The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Junos | Juniper | 20.4 (including) | 20.4 (including) |
| Junos | Juniper | 20.4-r1 (including) | 20.4-r1 (including) |
| Junos | Juniper | 20.4-r1-s1 (including) | 20.4-r1-s1 (including) |
| Junos | Juniper | 20.4-r2 (including) | 20.4-r2 (including) |
| Junos | Juniper | 20.4-r2-s1 (including) | 20.4-r2-s1 (including) |
| Junos | Juniper | 20.4-r2-s2 (including) | 20.4-r2-s2 (including) |
| Junos | Juniper | 20.4-r3 (including) | 20.4-r3 (including) |
| Junos | Juniper | 20.4-r3-s1 (including) | 20.4-r3-s1 (including) |
| Junos | Juniper | 20.4-r3-s2 (including) | 20.4-r3-s2 (including) |
| Junos | Juniper | 20.4-r3-s3 (including) | 20.4-r3-s3 (including) |
| Junos | Juniper | 21.1 (including) | 21.1 (including) |
| Junos | Juniper | 21.1-r1 (including) | 21.1-r1 (including) |
| Junos | Juniper | 21.1-r1-s1 (including) | 21.1-r1-s1 (including) |
| Junos | Juniper | 21.1-r2 (including) | 21.1-r2 (including) |
| Junos | Juniper | 21.1-r2-s1 (including) | 21.1-r2-s1 (including) |
| Junos | Juniper | 21.1-r2-s2 (including) | 21.1-r2-s2 (including) |
| Junos | Juniper | 21.1-r3 (including) | 21.1-r3 (including) |
| Junos | Juniper | 21.1-r3-s1 (including) | 21.1-r3-s1 (including) |
| Junos | Juniper | 21.1-r3-s2 (including) | 21.1-r3-s2 (including) |
| Junos | Juniper | 21.2 (including) | 21.2 (including) |
| Junos | Juniper | 21.2-r1 (including) | 21.2-r1 (including) |
| Junos | Juniper | 21.2-r1-s1 (including) | 21.2-r1-s1 (including) |
| Junos | Juniper | 21.2-r1-s2 (including) | 21.2-r1-s2 (including) |
| Junos | Juniper | 21.2-r2 (including) | 21.2-r2 (including) |
| Junos | Juniper | 21.2-r2-s1 (including) | 21.2-r2-s1 (including) |
| Junos | Juniper | 21.2-r2-s2 (including) | 21.2-r2-s2 (including) |
| Junos | Juniper | 21.2-r3 (including) | 21.2-r3 (including) |
| Junos | Juniper | 21.2-r3-s1 (including) | 21.2-r3-s1 (including) |
| Junos | Juniper | 21.3 (including) | 21.3 (including) |
| Junos | Juniper | 21.3-r1 (including) | 21.3-r1 (including) |
| Junos | Juniper | 21.3-r1-s1 (including) | 21.3-r1-s1 (including) |
| Junos | Juniper | 21.3-r1-s2 (including) | 21.3-r1-s2 (including) |
| Junos | Juniper | 21.3-r2 (including) | 21.3-r2 (including) |
| Junos | Juniper | 21.3-r2-s1 (including) | 21.3-r2-s1 (including) |
| Junos | Juniper | 21.3-r2-s2 (including) | 21.3-r2-s2 (including) |
| Junos | Juniper | 21.4 (including) | 21.4 (including) |
| Junos | Juniper | 21.4-r1 (including) | 21.4-r1 (including) |
| Junos | Juniper | 21.4-r1-s1 (including) | 21.4-r1-s1 (including) |
| Junos | Juniper | 21.4-r1-s2 (including) | 21.4-r1-s2 (including) |
| Junos | Juniper | 21.4-r2 (including) | 21.4-r2 (including) |
| Junos | Juniper | 21.4-r2-s1 (including) | 21.4-r2-s1 (including) |
| Junos | Juniper | 21.4-r2-s2 (including) | 21.4-r2-s2 (including) |
| Junos | Juniper | 22.1-r1 (including) | 22.1-r1 (including) |
| Junos | Juniper | 22.1-r1-s1 (including) | 22.1-r1-s1 (including) |
| Junos | Juniper | 22.1-r1-s2 (including) | 22.1-r1-s2 (including) |
Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.