# CVE-2026-103401: Juniper Session Smart Router link following arbitrary file overwrite

Source: https://junglewise.ai/threats/cve-2026-103401-an-improper-link-resolution-before-file-access-link-following  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-28. Updated: 2026-10-28  
License: CC BY 4.0 with a link back

CVE-2026-103401 · Severity: high · CVSS 8.8 · Published 2026-10-28

Juniper's Session Smart Router and Conductor are network routing devices that direct traffic for enterprises. A flaw in their web API allows a local attacker to overwrite system files as root without authentication, potentially enabling system compromise or denial of service. Only Mist-managed routers and unmanaged routers are vulnerable; those connected to a Conductor are protected.

Technologies: [Juniper Networks Session Smart Conductor](https://junglewise.ai/threats/technologies/session-smart-conductor), [Juniper Networks Session Smart Router](https://junglewise.ai/threats/technologies/session-smart-router). Vendors: [Juniper Networks](https://junglewise.ai/threats/vendors/juniper-networks).

## Quick answers

**Is CVE-2026-103401 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103401 being exploited in the wild.

**How severe is CVE-2026-103401?** High severity, with a CVSS score of 8.8, published 28 October 2026.

**Which products and versions are affected?** Juniper Networks Session Smart Router; Juniper Networks Session Smart Conductor.

**Is there a fix for CVE-2026-103401?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-103401 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-103401?** Check whether you run Juniper Networks Session Smart Conductor or Juniper Networks Session Smart Router. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An improper link resolution (symlink following) vulnerability exists in unauthenticated web server API handlers. A local unprivileged user can exploit this to write arbitrary files with root privileges via symlink traversal. Exploitation is limited to Mist-managed routers and routers not yet onboarded to a Conductor; machines under Conductor management are not affected.

## Affected products

- Juniper Networks Session Smart Router
- Juniper Networks Session Smart Conductor

## Timeline

- 2026-10-28: disclosed

## References

- [https://supportportal.juniper.net/JSA112183](https://supportportal.juniper.net/JSA112183)

## Related threats

- [Juniper Session Smart Router OS command injection in AccessManager](https://junglewise.ai/threats/cve-2026-106079-an-improper-neutralization-of-special-elements-used-in-an-os)
- [Juniper Networks Session Smart Router integer underflow in DHCP decoder](https://junglewise.ai/threats/cve-2026-103411-an-integer-underflow-vulnerability-in-dhcpmessagedecoder-in)
- [Juniper Networks Session Smart Router integer overflow in DPI certificate scanner](https://junglewise.ai/threats/cve-2026-103410-an-integer-overflow-vulnerability-in-the-dpi-certificate-scanner)
- [Juniper Networks Session Smart Router missing authentication](https://junglewise.ai/threats/cve-2026-103409-a-missing-authentication-for-critical-function-vulnerability-in)
- [Juniper Networks Session Smart Router stack buffer overflow in DHCP client](https://junglewise.ai/threats/cve-2026-103408-a-stack-buffer-overflow-vulnerability-in-the-dhcp-client-in)