CVE-2026-0203

Junos OS: Receipt of a specifically malformed ICMP packet causes an FPC restart

MEDIUM

6.5

CVSS Score

Published: January 15, 2026 at 08:17 PM UTC

Updated: June 17, 2026 at 10:10 AM UTC

1 product affected across 1 vendorJunos

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

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 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

v < 21.2v < 21.2R3-S921.4 ≤ v < 21.4R3-S1022.2 ≤ v < 22.2R3-S722.3 ≤ v < 22.3R3-S422.4 ≤ v < 22.4R3-S523.2 ≤ v < 23.2R2-S323.4 ≤ v < 23.4R2-S324.2 ≤ v < 24.2R1-S2, 24.2R221.2 21.2 r1 21.2 r1-s1 21.2 r1-s2 21.2 r2 21.2 r2-s1 21.2 r2-s2 21.2 r3 21.2 r3-s1 21.2 r3-s2 21.2 r3-s3 21.2 r3-s4 21.2 r3-s5 21.2 r3-s6 21.2 r3-s7 21.2 r3-s8 21.4 21.4 r1 21.4 r1-s1 21.4 r1-s2 21.4 r2 21.4 r2-s1 21.4 r2-s2 21.4 r3 21.4 r3-s1 21.4 r3-s2 21.4 r3-s3 21.4 r3-s4 21.4 r3-s5 21.4 r3-s6 21.4 r3-s7 21.4 r3-s8 21.4 r3-s9 22.2 22.2 r1 22.2 r1-s1 22.2 r1-s2 22.2 r2 22.2 r2-s1 22.2 r2-s2 22.2 r3 22.2 r3-s1 22.2 r3-s2 22.2 r3-s3 22.2 r3-s4 22.2 r3-s5 22.2 r3-s6 22.3 22.3 r1 22.3 r1-s1 22.3 r1-s2 22.3 r2 22.3 r2-s1 22.3 r2-s2 22.3 r3 22.3 r3-s1 22.3 r3-s2 22.3 r3-s3 22.4 22.4 r1 22.4 r1-s1 22.4 r1-s2 22.4 r2 22.4 r2-s1 22.4 r2-s2 22.4 r3 22.4 r3-s1 22.4 r3-s2 22.4 r3-s3 22.4 r3-s4 23.2 23.2 r1 23.2 r1-s1 23.2 r1-s2 23.2 r2 23.2 r2-s1 23.2 r2-s2 23.4 23.4 r1 23.4 r1-s1 23.4 r1-s2 23.4 r2 23.4 r2-s1 23.4 r2-s2 24.2 24.2 r1 24.2 r1-s1 24.2 r2

Affected range stops below 21.2R3-S9, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.4R3-S10, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.2R3-S7, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.3R3-S4, so it looks safe — our inference, not a vendor statement

Affected range stops below 22.4R3-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 23.2R2-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 23.4R2-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 24.2R1-S2, 24.2R2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

Vendor Advisory

Source: cverecord

https://supportportal.juniper.net/JSA104294

Vendor Advisory

Source: cverecord

https://kb.juniper.net/JSA104294

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMjuniper

Attack Vector: ADJACENT_NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-755

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