CVE-2026-0203
- CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published: 2026-01-15T21:16:05.457
An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS allows an unauthenticated, network-adjacent attacker sending a specifically malformed ICMP packet to cause an FPC to crash and restart, resulting in a Denial of Service (DoS).
When an ICMP packet is received with a specifically malformed IP header value, the FPC receiving the packet crashes and restarts. Due to the specific type of malformed packet, adjacent upstream routers would not forward the packet, limiting the attack surface to adjacent networks.
This issue only affects ICMPv4. ICMPv6 is not vulnerable to this issue.
This issue affects Junos OS:
* all versions before 21.2R3-S9,
* from 21.4 before 21.4R3-S10,
* from 22.2 before 22.2R3-S7,
* from 22.3 before 22.3R3-S4,
* from 22.4 before 22.4R3-S5,
* from 23.2 before 23.2R2-S3,
* from 23.4 before 23.4R2-S3,
* from 24.2 before 24.2R1-S2, 24.2R2.
Related CVE by CWE
No related CWE found.
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How to fix CVE-2026-0203
Description: An Improper Handling of Exceptional Conditions vulnerability in packet processing of Juniper Networks Junos OS allows an unauthenticated, network-adjacent attacker sending a specifically malformed ICMP packet to cause an FPC to crash and restart, resulting in a Denial of Service (DoS). When an ICMP packet is received with a specifically malformed IP header value, the […]
Exploit Difficulty: EASY
⏱️ Time to exploit: < 1 hour
🛠️ Required skills: Basic web security knowledge
💰 Public exploits: Likely available
How to Fix:
- Check if you're running the affected product
- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access
- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)
- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations
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No vendor/product data available.