CVE-2026-0243 Overview
CVE-2026-0243 is a denial of service (DoS) vulnerability affecting Palo Alto Networks Prisma SD-WAN ION devices. An unauthenticated attacker on an adjacent network can send a specially crafted IPv6 packet to trigger a system disruption on the targeted device. The flaw is tracked under [CWE-606: Unchecked Input for Loop Condition] and primarily impacts service availability rather than confidentiality or integrity. Palo Alto Networks published the advisory on May 13, 2026.
Critical Impact
A single malformed IPv6 packet from an adjacent network can disrupt Prisma SD-WAN ION device operation, degrading branch connectivity and SD-WAN traffic forwarding.
Affected Products
- Palo Alto Networks Prisma SD-WAN ION devices
- Refer to the Palo Alto Networks Security Advisory for affected software versions
- Deployments exposing IPv6 on adjacent network segments
Discovery Timeline
- 2026-05-13 - CVE-2026-0243 published to NVD
- 2026-05-13 - Last updated in NVD database
Technical Details for CVE-2026-0243
Vulnerability Analysis
The vulnerability resides in the IPv6 packet processing path of Prisma SD-WAN ION devices. A specially crafted IPv6 packet causes the device to enter an unintended processing state, resulting in a denial of service condition. The flaw is categorized under [CWE-606: Unchecked Input for Loop Condition], indicating that attacker-controlled input influences loop behavior without proper validation. Successful exploitation disrupts SD-WAN functionality, which can sever branch-to-hub connectivity and impact downstream applications relying on the ION device for transport.
The attack requires no authentication and no user interaction. The attacker must be positioned on an adjacent network segment to deliver the malicious IPv6 packet. Confidentiality and integrity remain unaffected, but availability impact on the target device is high. The reported scope does not extend beyond the targeted ION device, though service interruption can cascade through dependent network paths.
Root Cause
The root cause is improper handling of malformed or attacker-influenced fields within an IPv6 packet during parsing. The device fails to bound or validate the input controlling a processing loop, producing a condition that disrupts normal operation. Vendor advisory details describe the issue as a recoverable system disruption rather than persistent corruption.
Attack Vector
The attack vector is adjacent network (AV:A). An attacker on the same broadcast or routed link as the ION device crafts an IPv6 packet with fields that trigger the parsing flaw. The packet is transmitted to the device, and processing of that single packet is sufficient to cause the denial of service. Remote attackers outside the adjacent segment cannot directly reach the vulnerable code path.
No public proof-of-concept exploit is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the Palo Alto Networks Security Advisory for technical specifics.
Detection Methods for CVE-2026-0243
Indicators of Compromise
- Unexpected reboots, crashes, or service restarts on Prisma SD-WAN ION devices
- Loss of SD-WAN tunnel connectivity from a specific branch coinciding with IPv6 traffic spikes
- Anomalous IPv6 packets with malformed extension headers or oversized options originating from adjacent segments
Detection Strategies
- Monitor device health and uptime telemetry exported by Prisma SD-WAN ION devices for abrupt availability changes
- Inspect IPv6 traffic on management and LAN-facing interfaces using IDS signatures targeting malformed IPv6 headers
- Correlate device crash events with packet captures from adjacent segments to identify trigger traffic
Monitoring Recommendations
- Enable SNMP and syslog forwarding from ION devices to a centralized SIEM for real-time availability alerting
- Baseline normal IPv6 traffic volumes and packet structures on each branch segment
- Alert on repeated link-local IPv6 traffic from unexpected sources adjacent to ION devices
How to Mitigate CVE-2026-0243
Immediate Actions Required
- Review the Palo Alto Networks Security Advisory and identify ION devices running affected software versions
- Apply vendor-supplied fixed releases as soon as they are available for your deployment
- Restrict adjacent network access to ION device interfaces using port security, VLAN segmentation, and access control lists
Patch Information
Palo Alto Networks has published advisory details and remediation guidance at the vendor security advisory page. Administrators should consult the advisory for the specific fixed versions applicable to their Prisma SD-WAN ION software train and schedule upgrades through standard change management.
Workarounds
- Disable IPv6 on interfaces where it is not required, reducing the attack surface for malformed IPv6 packets
- Enforce strict layer-2 segmentation so that only trusted devices share an adjacent network with ION appliances
- Deploy upstream filtering on switches to drop malformed IPv6 extension headers before they reach the ION device
- Limit physical and logical access to branch network segments hosting ION devices
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
