Junos OS: Improper Handling of Length Parameter Inconsistency
CVE-2025-30659 is a high-severity improper handling of length parameter inconsistency vulnerability in Junos OS from Juniper Networks, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 21.4*, 22.2R3-S6, 22.4R3-S6 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 0.43% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Junos OS to 21.4* or 22.2R3-S6 or 22.4R3-S6 or 23.2R2-S3, whichever matches your release line, or a later version.
- Read the advisory on supportportal.juniper.net for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Juniper Networks | Junos OS | 21.4R1 up to, but not including, 21.4*; 22.2 up to, but not including, 22.2R3-S6; 22.4 up to, but not including, 22.4R3-S6; 23.2 up to, but not including, 23.2R2-S3; 23.4 up to, but not including, 23.4R2-S4; 24.2 up to, but not including, 24.2R2 | 21.4*, 22.2R3-S6, 22.4R3-S6, 23.2R2-S3, 23.4R2-S4, 24.2R2 |
| Juniper Networks | Junos | 21.4; 22.2; 22.4; 23.2; 23.4; 24.2 | Not stated |
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
- NetworkCan be exploited remotely over a network, including the internet.
- 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
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (juniper.net).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.7 | High | CNA (juniper.net) |
| CVSS 3.1 | 7.5 | High | CNA (juniper.net) |
Official description
An Improper Handling of Length Parameter Inconsistency vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). When a device configured for Secure Vector Routing (SVR) receives a specifically malformed packet the PFE will crash and restart. This issue affects Junos OS on SRX Series: * All 21.4 versions, * 22.2 versions before 22.2R3-S6, * 22.4 versions before 22.4R3-S6, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R2. This issue does not affect versions before 21.4.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Handling of Length Parameter Inconsistency
The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.
How developers prevent this class of flaw
- When processing structured incoming data containing a size field followed by raw data, ensure that you identify and resolve any inconsistencies between the size field and the actual size of the data.
- Do not let the user control the size of the buffer.
- Validate that the length of the user-supplied data is consistent with the buffer size.
More Improper Handling of Length Parameter Inconsistency vulnerabilities (CWE-130)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in Junos OS
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
Recent Improper Handling of Length Parameter Inconsistency vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.4 High severity
- 7.5 High severity
Spotted an error? Tell us.