CyberSecBulletin
CVE-2025-59960NVD status: Analyzed

Junos OS: Improper Check for Unusual or Exceptional Conditions

Published Updated By the CyberSecBulletin desk

CVE-2025-59960 is a high-severity improper check for unusual or exceptional conditions vulnerability in Junos OS from Juniper Networks, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 21.2R3-S10, 21.4R3-S12, 22.2* as the first without the flaw, so updating Junos OS to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.25% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Junos OS to 21.2R3-S10 or 21.4R3-S12 or 22.2* or 22.4R3-S8, whichever matches your release line, or a later version.
  2. Update Junos OS Evolved to 21.4R3-S12-EVO or 22.2* or 22.4R3-S8-EVO or 23.2R2-S5-EVO, whichever matches your release line, or a later version.
  3. Update Junos to 21.2 or a later version.
  4. Read the advisory on kb.juniper.net for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Juniper NetworksJunos OSbefore 21.2R3-S10; 21.4 up to, but not including, 21.4R3-S12; 22.2 up to, but not including, 22.2*; 22.4 up to, but not including, 22.4R3-S8; 23.2 up to, but not including, 23.2R2-S5; 23.4 up to, but not including, 23.4R2-S6; 24.2 up to, but not including, 24.2R2-S2; 24.4 up to, but not including, 24.4R2; and 1 more ranges21.2R3-S10, 21.4R3-S12, 22.2*, 22.4R3-S8, 23.2R2-S5, 23.4R2-S6
Juniper NetworksJunos OS Evolvedbefore 21.4R3-S12-EVO; 22.2 up to, but not including, 22.2*; 22.4 up to, but not including, 22.4R3-S8-EVO; 23.2 up to, but not including, 23.2R2-S5-EVO; 23.4 up to, but not including, 23.4R2-S6-EVO; 24.2 up to, but not including, 24.2R2-S2-EVO; 24.4 up to, but not including, 24.4R2-EVO; 25.2 up to, but not including, 25.2R1-S1-EVO, 25.2R2-EVO21.4R3-S12-EVO, 22.2*, 22.4R3-S8-EVO, 23.2R2-S5-EVO, 23.4R2-S6-EVO, 24.2R2-S2-EVO
Juniper NetworksJunosbefore 21.2; 21.2; 21.4; 22.2; 22.4; 23.2; 23.4; 24.2; and 2 more ranges21.2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H. Scored by CNA (juniper.net).

Scoring systemScoreSeverityScored by
CVSS 4.06.3MediumCNA (juniper.net)
CVSS 3.17.4HighCNA (juniper.net)

Official description

An Improper Check for Unusual or Exceptional Conditions vulnerability in the Juniper DHCP service (jdhcpd) of Juniper Networks Junos OS and Junos OS Evolved allows a DHCP client in one subnet to exhaust the address pools of other subnets, leading to a Denial of Service (DoS) on the downstream DHCP server. By default, the DHCP relay agent inserts its own Option 82 information when forwarding client requests, optionally replacing any Option 82 information provided by the client. When a specific DHCP DISCOVER is received in 'forward-only' mode with Option 82, the device should drop the message unless 'trust-option82' is configured. Instead, the DHCP relay forwards these packets to the DHCP server unmodified, which uses up addresses in the DHCP server's address pool, ultimately leading to address pool exhaustion. This issue affects Junos OS: * all versions before 21.2R3-S10, * from 21.4 before 21.4R3-S12, * all versions of 22.2, * from 22.4 before 22.4R3-S8, * from 23.2 before 23.2R2-S5, * from 23.4 before 23.4R2-S6, * from 24.2 before 24.2R2-S2, * from 24.4 before 24.4R2, * from 25.2 before 25.2R1-S1, 25.2R2. Junos OS Evolved: * all versions before 21.4R3-S12-EVO, * all versions of 22.2-EVO, * from 22.4 before 22.4R3-S8-EVO, * from 23.2 before 23.2R2-S5-EVO, * from 23.4 before 23.4R2-S6-EVO, * from 24.2 before 24.2R2-S2-EVO, * from 24.4 before 24.4R2-EVO, * from 25.2 before 25.2R1-S1-EVO, 25.2R2-EVO.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Check for Unusual or Exceptional Conditions

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Choose languages with features such as exception handling that force the programmer to anticipate unusual conditions that may generate exceptions. Custom exceptions may need to be developed to handle unusual business-logic conditions. Be careful not to pass sensitive exceptions back to the user (CWE-209, CWE-248).
  • Check the results of all functions that return a value and verify that the value is expected.
  • If using exception handling, catch and throw specific exceptions instead of overly-general exceptions (CWE-396, CWE-397). Catch and handle exceptions as locally as possible so that exceptions do not propagate too far up the call stack (CWE-705). Avoid unchecked or uncaught exceptions where feasible (CWE-248).

More Improper Check for Unusual or Exceptional Conditions vulnerabilities (CWE-754)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other references

Other vulnerabilities in Junos OS

All Junos OS vulnerabilities

Recent Improper Check for Unusual or Exceptional Conditions vulnerabilities

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