---
id: "CVE-2026-103392"
kind: "vulnerability"
aliases: ["CVE-2026-103392"]
title: "Juniper Session Smart Router: oversized TCP SACK option corrupts session data"
severity: "medium"
cvss: 4.8
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "juniper", "network-appliance", "session-smart-router"]
not_affected_if: []
published_at: "2026-10-28T17:17:22+00:00"
first_seen_at: "2026-10-28T17:34:08+00:00"
updated_at: "2026-10-28T17:34:40+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-103392", "first_seen_at": "2026-10-28T17:34:08+00:00"}]
---

# Juniper Session Smart Router: oversized TCP SACK option corrupts session data

A flaw in how Juniper Session Smart Router processes TCP headers lets an out-of-bounds write happen when a transit packet carries an oversized SACK option length. An attacker can corrupt TCP payload data and possibly desynchronize sessions passing through the device.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-28T17:34:08+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-103392

## From the sources

An Out-of-Bounds Write vulnerability in the TCP header processing in Juniper Networks Session Smart Router allows an attacker to corrupt TCP payload data and potentially cause session desynchronization via a transit TCP packet with an oversized SACK option length.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_