CVE-2026-0203 (GCVE-0-2026-0203)

Vulnerability from cvelistv5 – Published: 2026-01-15 20:17 – Updated: 2026-01-15 21:11
VLAI?
Title
Junos OS: Receipt of a specifically malformed ICMP packet causes an FPC restart
Summary
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.
Severity ?
6.5 (Medium)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.1 (High)
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M/U:Amber
CWE
  • CWE-755 - Improper Handling of Exceptional Conditions
Assigner
References
Impacted products
Vendor Product Version
Juniper Networks Junos OS Affected: 0 , < 21.2R3-S9 (semver)
Affected: 21.4 , < 21.4R3-S10 (semver)
Affected: 22.2 , < 22.2R3-S7 (semver)
Affected: 22.3 , < 22.3R3-S4 (semver)
Affected: 22.4 , < 22.4R3-S5 (semver)
Affected: 23.2 , < 23.2R2-S3 (semver)
Affected: 23.4 , < 23.4R2-S3 (semver)
Affected: 24.2 , < 24.2R1-S2, 24.2R2 (semver)
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ICMPv6 is not vulnerable to this issue.\\n\\nThis issue affects Junos OS:\\u00a0\\n\\n\\n\\n  *  all versions before 21.2R3-S9,\\u00a0\\n  *  from 21.4 before 21.4R3-S10,\\u00a0\\n  *  from 22.2 before 22.2R3-S7,\\u00a0\\n  *  from 22.3 before 22.3R3-S4,\\u00a0\\n  *  from 22.4 before 22.4R3-S5,\\u00a0\\n  *  from 23.2 before 23.2R2-S3,\\u00a0\\n  *  from 23.4 before 23.4R2-S3,\\u00a0\\n  *  from 24.2 before 24.2R1-S2, 24.2R2.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"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).\u003cbr\u003e\u003cbr\u003e\\n\\n\u003cspan style=\\\"background-color: rgb(255, 255, 255);\\\"\u003eWhen 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.\u003cbr\u003e\u003cbr\u003e\u003c/span\u003eThis issue only affects ICMPv4. ICMPv6 is not vulnerable to this issue.\u003cbr\u003e\u003cbr\u003e\u003cp\u003eThis issue affects Junos OS:\u0026nbsp;\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cul\u003e\u003cli\u003eall versions before 21.2R3-S9,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 21.4 before 21.4R3-S10,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 22.2 before 22.2R3-S7,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 22.3 before 22.3R3-S4,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 22.4 before 22.4R3-S5,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.2 before 23.2R2-S3,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.4 before 23.4R2-S3,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 24.2 before 24.2R1-S2, 24.2R2.\u003c/li\u003e\u003c/ul\u003e\u003cp\u003e\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-755\", \"description\": \"CWE-755 Improper Handling of Exceptional Conditions\"}]}], \"providerMetadata\": {\"orgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"shortName\": \"juniper\", \"dateUpdated\": \"2026-01-15T20:18:03.924Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-0203\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-01-15T21:11:32.119Z\", \"dateReserved\": \"2025-10-29T20:57:34.631Z\", \"assignerOrgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"datePublished\": \"2026-01-15T20:17:24.552Z\", \"assignerShortName\": \"juniper\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.