Junos OS (SRX firewalls)
CVE-2024-39536: Flaps of BFD sessions with authentication cause a ppmd memory leak
A Missing Release of Memory after Effective Lifetime vulnerability in the Periodic Packet Management Daemon (ppmd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a Denial-of-Service (DoS).
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Junos OS 0 | 21.2R3-S8 or later |
| Junos OS 21.4 | 21.4R3-S7 or later |
| Junos OS 22.1 | 22.1R3-S4 or later |
| Junos OS 22.2 | 22.2R3-S4 or later |
| Junos OS 22.3 | 22.3R3 or later |
| Junos OS 22.4 | 22.4R2-S2, 22.4R3 or later |
| Junos OS Evolved 21.2-EVO | 21.2R3-S8-EVO or later |
| Junos OS Evolved 21.4-EVO | 21.4R3-S7-EVO or later |
| Junos OS Evolved 22.2-EVO | 22.2R3-S4-EVO or later |
| Junos OS Evolved 22.3-EVO | 22.3R3-EVO or later |
| Junos OS Evolved 22.4-EVO | 22.4R3-EVO or later |
| Junos OS Evolved 23.2-EVO | 23.2R1-EVO or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
A Missing Release of Memory after Effective Lifetime vulnerability in the Periodic Packet Management Daemon (ppmd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated adjacent attacker to cause a
Denial-of-Service (DoS).
When a BFD session configured with authentication flaps, ppmd memory can leak. Whether the leak happens depends on a race condition which is outside the attackers control. This issue only affects BFD operating in distributed aka delegated (which is the default behavior) or inline mode.
Whether the leak occurs can be monitored with the following CLI command:
> show ppm request-queue
FPC Pending-request fpc0 2 request-total-pending: 2
where a continuously increasing number of pending requests is indicative of the leak.
This issue affects:
Junos OS:
- All versions before 21.2R3-S8,
- 21.4 versions before 21.4R3-S7,
- 22.1 versions before 22.1R3-S4,
- 22.2 versions before 22.2R3-S4,
- 22.3 versions before 22.3R3,
- 22.4 versions before 22.4R2-S2, 22.4R3.
Junos OS Evolved: * All versions before 21.2R3-S8-EVO, * 21.4-EVO versions before 21.4R3-S7-EVO, * 22.2-EVO versions before 22.2R3-S4-EVO, * 22.3-EVO versions before 22.3R3-EVO, * 22.4-EVO versions before 22.4R3-EVO.
Am I affected?
To be exposed to this issue, BFD with authentication like in the following examples needs to be
configured:
[ protocols <protocol> ... bfd-liveness-detection authentication ] [ routing-options ... bfd-liveness-detection authentication ]
Workarounds
There are no known workarounds for this issue.
Exploitation
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.