What is CVE-2024-21594?

CVE-2024-21594 is a medium-severity vulnerability in Juniper Junos, classified under Heap-based Buffer Overflow. CVSS score: 5.5/10. Published 2024-01-12.

How severe is CVE-2024-21594?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Buffer overflow in Juniper Junos

CVE-2024-21594

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.

Vulnerability class: Buffer Overflow

Published 2024-01-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (6.0th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 6.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Juniper Junos — versions 20.4, 21.1, 21.2
Juniper Networks Junos OS — versions 0, 21.1, 21.2

Weakness classification (CWE)

References

supportportal.juniper.net/JSA75733 (vendor-advisory, Vendor Advisory)
www.first.org/cvss/calculator/4.0 (technical-description, Vendor Advisory)

Frequently asked questions

What is CVE-2024-21594?: CVE-2024-21594 is a medium-severity vulnerability in Juniper Junos, classified under Heap-based Buffer Overflow. CVSS score: 5.5/10. Published 2024-01-12.
How severe is CVE-2024-21594?: Medium severity. CVSS v3 base score is 5.5 out of 10.