CVE-2025-21591
HIGHDescription
A Buffer Access with Incorrect Length Value vulnerability in the jdhcpd daemon of Juniper Networks Junos OS, when DHCP snooping is enabled, allows an unauthenticated, adjacent, attacker to send a DHCP packet with a malformed DHCP option to cause jdhcp to crash creating a Denial of Service (DoS) condition. Continuous receipt of these DHCP packets using the malformed DHCP Option will create a sustained Denial of Service (DoS) condition. This issue affects Junos OS: * from 23.1 before 23.2R2-S3, * from 23.4 before 23.4R2-S3, * from 24.2 before 24.2R2. This issue isn't applicable to any versions of Junos OS before 23.1R1. This issue doesn't affect vSRX Series which doesn't support DHCP Snooping. This issue doesn't affect Junos OS Evolved. There are no indicators of compromise for this issue.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
TridentStack Control tracks known vulnerabilities across your Windows, macOS, and Linux fleet and shows the fix as soon as one is published. See how it works
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 25% of all known CVEs.
References
Related Vulnerabilities
Other CWE-805 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2020-14509 | Critical | 9.8 | 2.0% | - | Fix |
| CVE-2025-23319 | High | 8.1 | 1.6% | - | Fix |
| CVE-2024-24851 | High | 7.5 | 1.4% | - | - |
| CVE-2021-31885 | High | 7.5 | 1.2% | - | Fix |
| CVE-2023-20049 | High | 8.6 | 1.0% | - | Fix |
| CVE-2020-16101 | High | 7.5 | 1.0% | - | Fix |
Common questions
How do I fix CVE-2025-21591?
No published fix for CVE-2025-21591 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2025-21591 being actively exploited?
Not that we know of. CVE-2025-21591 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.32% is the estimated probability that it will be exploited in the next 30 days. That is higher than 25% of all scored CVEs.
How severe is CVE-2025-21591?
CVE-2025-21591 has a CVSS v3 base score of 7.4, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
Embed a live status badge for CVE-2025-21591
Markdown
[](https://tridentstack.com/cve/CVE-2025-21591)HTML
<a href="https://tridentstack.com/cve/CVE-2025-21591"><img src="https://tridentstack.com/cve/badge/CVE-2025-21591.svg" alt="CVE-2025-21591"></a>Find and fix vulnerabilities across your fleet
TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.
This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-01-26.