Session Smart Router: Authentication Bypass Using an Alternate Path or Channel
CVE-2025-21589 is a critical-severity authentication bypass using an alternate path or channel vulnerability in Session Smart Router from Juniper Networks, with a CVSS 3.1 base score of 9.8 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 5.6.17, 6.1.12-lts, 6.2.8-lts as the first without the flaw, so updating Session Smart Router to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.55% chance of exploitation within 30 days, higher than 75% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Session Smart Router to 5.6.17 or 6.1.12-lts or 6.2.8-lts or 6.3.3-r2, whichever matches your release line, or a later version.
- Update Session Smart Conductor to 5.6.17 or 6.1.12-lts or 6.2.8-lts or 6.3.3-r2, whichever matches your release line, or a later version.
- Update WAN Assurance Managed Router to 5.6.17 or 6.1.12-lts or 6.2.8-lts or 6.3.3-r2, whichever matches your release line, or a later version.
- 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 | Session Smart Router | 5.6.7 up to, but not including, 5.6.17; 6.1 up to, but not including, 6.1.12-lts; 6.2 up to, but not including, 6.2.8-lts; 6.3 up to, but not including, 6.3.3-r2 | 5.6.17, 6.1.12-lts, 6.2.8-lts, 6.3.3-r2 |
| Juniper Networks | Session Smart Conductor | 5.6.7 up to, but not including, 5.6.17; 6.1 up to, but not including, 6.1.12-lts; 6.2 up to, but not including, 6.2.8-lts; 6.3 up to, but not including, 6.3.3-r2 | 5.6.17, 6.1.12-lts, 6.2.8-lts, 6.3.3-r2 |
| Juniper Networks | WAN Assurance Managed Router | 5.6.7 up to, but not including, 5.6.17; 6.1 up to, but not including, 6.1.12-lts; 6.2 up to, but not including, 6.2.8-lts; 6.3 up to, but not including, 6.3.3-r2 | 5.6.17, 6.1.12-lts, 6.2.8-lts, 6.3.3-r2 |
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
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (juniper.net).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (juniper.net) |
| CVSS 3.1 | 9.8 | Critical | CNA (juniper.net) |
Official description
An Authentication Bypass Using an Alternate Path or Channel vulnerability in Juniper Networks Session Smart Router may allows a network-based attacker to bypass authentication and take administrative control of the device. This issue affects Session Smart Router: * from 5.6.7 before 5.6.17, * from 6.0 before 6.0.8 (affected from 6.0.8), * from 6.1 before 6.1.12-lts, * from 6.2 before 6.2.8-lts, * from 6.3 before 6.3.3-r2; This issue affects Session Smart Conductor: * from 5.6.7 before 5.6.17, * from 6.0 before 6.0.8 (affected from 6.0.8), * from 6.1 before 6.1.12-lts, * from 6.2 before 6.2.8-lts, * from 6.3 before 6.3.3-r2; This issue affects WAN Assurance Managed Routers: * from 5.6.7 before 5.6.17, * from 6.0 before 6.0.8 (affected from 6.0.8), * from 6.1 before 6.1.12-lts, * from 6.2 before 6.2.8-lts, * from 6.3 before 6.3.3-r2.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass Using an Alternate Path or Channel
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
How developers prevent this class of flaw
- Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
More Authentication Bypass Using an Alternate Path or Channel vulnerabilities (CWE-288)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Session Smart Router
- 8.8 High severity
- 7.1 High severity
- 7.5 High severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
Recent Authentication Bypass Using an Alternate Path or Channel vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
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