CVE-2024-21601
Junos OS: SRX Series: Due to an error in processing TCP events flowd will crash
A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the Flow-processing Daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos).
On SRX Series devices when two different threads try to simultaneously process a queue which is used for TCP events flowd will crash. One of these threads can not be triggered externally, so the exploitation of this race condition is outside the attackers direct control.
Continued exploitation of this issue will lead to a sustained DoS.
This issue affects Juniper Networks Junos OS:
- 21.2 versions earlier than 21.2R3-S5;
- 21.3 versions earlier than 21.3R3-S5;
- 21.4 versions earlier than 21.4R3-S4;
- 22.1 versions earlier than 22.1R3-S3;
- 22.2 versions earlier than 22.2R3-S1;
- 22.3 versions earlier than 22.3R2-S2, 22.3R3;
- 22.4 versions earlier than 22.4R2-S1, 22.4R3.
This issue does not affect Juniper Networks Junos OS versions earlier than 21.2R1.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Junos OS: SRX Series: Due to an error in processing TCP events flowd will crash
A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the Flow-processing Daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos).
On SRX Series devices when two different threads try to simultaneously process a queue which is used for TCP events flowd will crash. One of these threads can not be triggered externally, so the exploitation of this race condition is outside the attackers direct control.
Continued exploitation of this issue will lead to a sustained DoS.
This issue affects Juniper Networks Junos OS:
- 21.2 versions earlier than 21.2R3-S5;
- 21.3 versions earlier than 21.3R3-S5;
- 21.4 versions earlier than 21.4R3-S4;
- 22.1 versions earlier than 22.1R3-S3;
- 22.2 versions earlier than 22.2R3-S1;
- 22.3 versions earlier than 22.3R2-S2, 22.3R3;
- 22.4 versions earlier than 22.4R2-S1, 22.4R3.
This issue does not affect Juniper Networks Junos OS versions earlier than 21.2R1.
- Record
CVE-2024-21601- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-362
- Updated
- 2026-11-02
EUVDEUVD-2024-19249
A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the Flow-processing Daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos).
On SRX Series devices when two different threads try to simultaneously process a queue which is used for TCP events flowd will crash. One of these threads can not be triggered externally, so the exploitation of this race condition is outside the attackers direct control.
Continued exploitation of this issue will lead to a sustained DoS.
This issue affects Juniper Networks Junos OS:
- 21.2 versions earlier than 21.2R3-S5;
- 21.3 versions earlier than 21.3R3-S5;
- 21.4 versions earlier than 21.4R3-S4;
- 22.1 versions earlier than 22.1R3-S3;
- 22.2 versions earlier than 22.2R3-S1;
- 22.3 versions earlier than 22.3R2-S2, 22.3R3;
- 22.4 versions earlier than 22.4R2-S1, 22.4R3.
This issue does not affect Juniper Networks Junos OS versions earlier than 21.2R1.
- Record
EUVD-2024-19249- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-5mjf-6gr5-jvh8
A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')...
A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the Flow-processing Daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos).
On SRX Series devices when two different threads try to simultaneously process a queue which is used for TCP events flowd will crash. One of these threads can not be triggered externally, so the exploitation of this race condition is outside the attackers direct control.
Continued exploitation of this issue will lead to a sustained DoS.
This issue affects Juniper Networks Junos OS:
- 21.2 versions earlier than 21.2R3-S5;
- 21.3 versions earlier than 21.3R3-S5;
- 21.4 versions earlier than 21.4R3-S4;
- 22.1 versions earlier than 22.1R3-S3;
- 22.2 versions earlier than 22.2R3-S1;
- 22.3 versions earlier than 22.3R2-S2, 22.3R3;
- 22.4 versions earlier than 22.4R2-S1, 22.4R3.
This issue does not affect Juniper Networks Junos OS versions earlier than 21.2R1.
- Record
GHSA-5mjf-6gr5-jvh8- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-362
- Updated
- 2026-11-02
NVD
A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the Flow-processing Daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos).
On SRX Series devices when two different threads try to simultaneously process a queue which is used for TCP events flowd will crash. One of these threads can not be triggered externally, so the exploitation of this race condition is outside the attackers direct control.
Continued exploitation of this issue will lead to a sustained DoS.
This issue affects Juniper Networks Junos OS:
- 21.2 versions earlier than 21.2R3-S5;
- 21.3 versions earlier than 21.3R3-S5;
- 21.4 versions earlier than 21.4R3-S4;
- 22.1 versions earlier than 22.1R3-S3;
- 22.2 versions earlier than 22.2R3-S1;
- 22.3 versions earlier than 22.3R2-S2, 22.3R3;
- 22.4 versions earlier than 22.4R2-S1, 22.4R3.
This issue does not affect Juniper Networks Junos OS versions earlier than 21.2R1.
- Record
CVE-2024-21601- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-362
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2024-21601 is a medium vulnerability (CVSS 5.9) in Juniper Junos, published January 12, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.45%, the 39th percentile. No source names a fixed version.