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Fencer Intel
high 7.4

CVE-2025-21591 json

Junos OS: An unauthenticated adjacent attacker sending a malformed DHCP packet causes jdhcpd to crash

published last yr. modified 4mo ago also EUVD-2025-10536

cvss
7.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits
0
none known

Summary

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.

Patch / fix

  • Juniper Networks Junos OS 23.2R2-S3, 23.4R2-S3, 24.2R2

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.4 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CNA 4.0 7.1 CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:U/V:C/RE:M/U:Green
CNA 4.0 7.1 CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:C/RE:M/U:Green

Affected products

  • Juniper Networks Junos OS

Classification

Weakness
  • CWE-805 Buffer Access with Incorrect Length Value

References

Sources

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