An Improper Input Validation vulnerability in the syslog stream TCP transport of Juniper…
CVE-2025-30649 is a high-severity improper input validation 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 22.2R3-S6, 22.4R3-S4, 23.2R2-S3 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 22.2R3-S6 or 22.4R3-S4 or 23.2R2-S3 or 23.4R2-S4, whichever matches your release line, or a later version.
- Update Junos to 22.2 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 | before 22.2R3-S6; 22.4 up to, but not including, 22.4R3-S4; 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, 24.2R1-S2, 24.2R2 | 22.2R3-S6, 22.4R3-S4, 23.2R2-S3, 23.4R2-S4, 24.2R1-S2, 24.2R2 |
| Juniper Networks | Junos | before 22.2; 22.2; 22.4; 23.2; 23.4; 24.2 | 22.2 |
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
- 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 Input Validation vulnerability in the syslog stream TCP transport of Juniper Networks Junos OS on MX240, MX480 and MX960 devices with MX-SPC3 Security Services Card allows an unauthenticated, network-based attacker, to send specific spoofed packets to cause a CPU Denial of Service (DoS) to the MX-SPC3 SPUs. Continued receipt and processing of these specific packets will sustain the DoS condition. This issue affects Junos OS: * All versions before 22.2R3-S6, * from 22.4 before 22.4R3-S4, * from 23.2 before 23.2R2-S3, * from 23.4 before 23.4R2-S4, * from 24.2 before 24.2R1-S2, 24.2R2 An indicator of compromise will indicate the SPC3 SPUs utilization has spiked. For example: user@device> show services service-sets summary Service sets CPU Interface configured Bytes used Session bytes used Policy bytes used utilization "interface" 1 "bytes" (percent%) "sessions" ("percent"%) "bytes" ("percent"%) 99.97 % OVLD <<<<<< look for high CPU usage
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
How developers prevent this class of flaw
- Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
- Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
- Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
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 Input Validation vulnerabilities
- 7.4 High severity
- 7.8 High severity
- 9.1 Critical severity
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
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