CVE-2024-21594: Juniper Networks Junos OS · Heap-based Buffer Overflow
Affects Juniper Networks Junos OSSource CVE Database V5
Not known to be exploited · CVSS 5.5 Medium · fixed in 22.3R2 : update Juniper Networks Junos OS when convenient.
Data as of 26 Oct 2026, 11:42 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 22.3R2, 22.2R3, 22.1R3-S1 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 12 Jan 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Juniper Networks Junos OS | Affected
| Fixed in
|
AI-suggested
European organizations should prioritize upgrading affected Junos OS versions to the latest patched releases as specified by Juniper Networks to remediate this vulnerability. If you cannot patch yet, organizations should implement strict access controls to limit local authenticated access to SRX 5000 Series devices, including enforcing strong authentication mechanisms and monitoring for unusual command execution patterns. Network segmentation and the use of jump hosts or bastion servers can reduce the risk of unauthorized local access. Additionally, continuous monitoring of device logs for the specific error message 'policies are out of sync for PFE node' can help detect exploitation attempts early. Incident response plans should include procedures for rapid NSD process restarts to minimize downtime. Regular security audits and vulnerability scanning of network devices should be conducted to ensure compliance with patch management policies. Finally, organizations should consider deploying intrusion detection or endpoint detection solutions capable of identifying anomalous local activity on network devices.
Description
A Heap-based Buffer Overflow vulnerability in the Network Services Daemon (NSD) of Juniper Networks Junos OS allows authenticated, low privileged, local attacker to cause a Denial of Service (DoS). On an SRX 5000 Series device, when executing a specific command repeatedly, memory is corrupted, which leads to a Flow Processing Daemon (flowd) crash. The NSD process has to be restarted to restore services. If this issue occurs, it can be checked with the following command: user@host> request security policies check The following log message can also be observed: Error: policies are out of sync for PFE node<number>.fpc<number>.pic<number>. This issue affects: Juniper Networks Junos OS on SRX 5000 Series * All versions earlier than 20.4R3-S6; * 21.1 versions earlier than 21.1R3-S5; * 21.2 versions earlier than 21.2R3-S4; * 21.3 versions earlier than 21.3R3-S3; * 21.4 versions earlier than 21.4R3-S3; * 22.1 versions earlier than 22.1R3-S1; * 22.2 versions earlier than 22.2R3; * 22.3 versions earlier than 22.3R2.