CVE-2026-21906 (GCVE-0-2026-21906)

Vulnerability from cvelistv5 – Published: 2026-01-15 20:20 – Updated: 2026-01-16 16:20
VLAI?
Title
Junos OS: SRX Series: With GRE performance acceleration enabled, receipt of a specific ICMP packet causes the PFE to crash
Summary
An Improper Handling of Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated network-based attacker sending a specific ICMP packet through a GRE tunnel to cause the PFE to crash and restart. When PowerMode IPsec (PMI) and GRE performance acceleration are enabled and the device receives a specific ICMP packet, a crash occurs in the SRX PFE, resulting in traffic loss. PMI is enabled by default, and GRE performance acceleration can be enabled by running the configuration command shown below. PMI is a mode of operation that provides IPsec performance improvements using Vector Packet Processing. Note that PMI with GRE performance acceleration is only supported on specific SRX platforms. This issue affects Junos OS on the SRX Series: * all versions before 21.4R3-S12,  * from 22.4 before 22.4R3-S8,  * from 23.2 before 23.2R2-S5,  * from 23.4 before 23.4R2-S5,  * from 24.2 before 24.2R2-S3,  * from 24.4 before 24.4R2-S1,  * from 25.2 before 25.2R1-S1, 25.2R2.
Severity ?
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Red
CWE
  • CWE-755 - Improper Handling of Exceptional Conditions
Assigner
References
Impacted products
Vendor Product Version
Juniper Networks Junos OS Affected: 0 , < 21.4R3-S12 (semver)
Affected: 22.4 , < 22.4R3-S8 (semver)
Affected: 23.2 , < 23.2R2-S5 (semver)
Affected: 23.4 , < 23.4R2-S5 (semver)
Affected: 24.2 , < 24.2R2-S3 (semver)
Affected: 24.4 , < 24.4R2-S1 (semver)
Affected: 25.2 , < 25.2R1-S1, 25.2R2 (semver)
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\"25.2R1-S1, 25.2R2\", \"versionType\": \"semver\"}], \"platforms\": [\"SRX Series\"], \"defaultStatus\": \"unaffected\"}], \"exploits\": [{\"lang\": \"en\", \"value\": \"Juniper SIRT is not aware of any malicious exploitation of this vulnerability.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Juniper SIRT is not aware of any malicious exploitation of this vulnerability.\", \"base64\": false}]}], \"solutions\": [{\"lang\": \"en\", \"value\": \"The following software releases have been updated to resolve this specific issue: Junos OS 21.4R3-S12, 22.4R3-S8, 23.2R2-S5, 23.4R2-S5, 24.2R2-S3, 24.4R2-S1, 25.2R1-S1, 25.2R2, 25.4R1, and all subsequent releases.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"The following software releases have been updated to resolve this specific issue: Junos OS 21.4R3-S12, 22.4R3-S8, 23.2R2-S5, 23.4R2-S5, 24.2R2-S3, 24.4R2-S1, 25.2R1-S1, 25.2R2, 25.4R1, and all subsequent releases.\", \"base64\": false}]}], \"datePublic\": \"2026-01-14T17:00:00.000Z\", \"references\": [{\"url\": \"https://supportportal.juniper.net/JSA106005\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://www.juniper.net/documentation/us/en/software/junos/vpn-ipsec/topics/topic-map/security-powermode-ipsec-vpn.html\", \"tags\": [\"technical-description\"]}, {\"url\": \"https://kb.juniper.net/JSA106005\", \"tags\": [\"vendor-advisory\"]}], \"workarounds\": [{\"lang\": \"en\", \"value\": \"*  Disable GRE performance acceleration via \u0027deactivate security flow gre-performance-acceleration\u0027\\nor\\n  *  Disable PMI:via \u0027set security flow power-mode-disable\u0027\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cul\u003e\u003cli\u003eDisable GRE performance acceleration via \u0027\u003ctt\u003edeactivate security flow gre-performance-acceleration\u003c/tt\u003e\u0027\u003cbr\u003eor\u003c/li\u003e\u003cli\u003eDisable PMI:via \u0027\u003ctt\u003eset security flow power-mode-disable\u003c/tt\u003e\u0027\u003c/li\u003e\u003c/ul\u003e\", \"base64\": false}]}], \"x_generator\": {\"engine\": \"Vulnogram 0.1.0-dev\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"An Improper Handling of Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated network-based attacker sending a specific ICMP packet through a GRE tunnel to cause the PFE to crash and restart.\\n\\nWhen PowerMode IPsec (PMI) and GRE performance acceleration are enabled and the device receives a specific ICMP packet, a crash occurs in the SRX PFE, resulting in traffic loss. PMI is enabled by default, and GRE performance acceleration can be enabled by running the configuration command shown below.\\u00a0PMI is a mode of operation that provides IPsec performance improvements using Vector Packet Processing.\\n\\nNote that PMI with GRE performance acceleration is only supported on specific SRX platforms.\\nThis issue affects Junos OS on the SRX Series:\\n\\n\\n\\n  *  all versions before 21.4R3-S12,\\u00a0\\n  *  from 22.4 before 22.4R3-S8,\\u00a0\\n  *  from 23.2 before 23.2R2-S5,\\u00a0\\n  *  from 23.4 before 23.4R2-S5,\\u00a0\\n  *  from 24.2 before 24.2R2-S3,\\u00a0\\n  *  from 24.4 before 24.4R2-S1,\\u00a0\\n  *  from 25.2 before 25.2R1-S1, 25.2R2.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cspan style=\\\"background-color: rgb(255, 255, 255);\\\"\u003eAn Improper Handling of Exceptional Conditions vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated network-based attacker sending a specific ICMP packet through a GRE tunnel to cause the PFE to crash and restart.\u003c/span\u003e\u003cbr\u003e\u003cbr\u003eWhen PowerMode IPsec (PMI) and GRE performance acceleration are enabled and the device receives a specific ICMP packet, a crash occurs in the SRX PFE, resulting in traffic loss. PMI is enabled by default, and GRE performance acceleration can be enabled by running the configuration command shown below.\u0026nbsp;PMI is a mode of operation that provides IPsec performance improvements using Vector Packet Processing.\u003cbr\u003e\u003cbr\u003eNote that PMI with GRE performance acceleration is only supported on specific SRX platforms.\u003cbr\u003e\u003cp\u003eThis issue affects Junos OS on the SRX Series:\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cul\u003e\u003cli\u003eall versions before 21.4R3-S12,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 22.4 before 22.4R3-S8,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.2 before 23.2R2-S5,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.4 before 23.4R2-S5,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 24.2 before 24.2R2-S3,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 24.4 before 24.4R2-S1,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 25.2 before 25.2R1-S1, 25.2R2.\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\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"This issue requires GRE performance acceleration to be enabled:\\n\\n\\n\\n[set security flow gre-performance-acceleration]\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"This issue requires GRE performance acceleration to be enabled:\u003cbr\u003e\u003cbr\u003e\\n\\n\u003ctt\u003e\u003cspan style=\\\"background-color: rgb(255, 255, 255);\\\"\u003e[set security flow gre-performance-acceleration]\u003c/span\u003e\u003c/tt\u003e\", \"base64\": false}]}], \"providerMetadata\": {\"orgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"shortName\": \"juniper\", \"dateUpdated\": \"2026-01-15T20:20:32.530Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-21906\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-01-16T16:20:14.792Z\", \"dateReserved\": \"2026-01-05T17:32:48.710Z\", \"assignerOrgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"datePublished\": \"2026-01-15T20:20:32.530Z\", \"assignerShortName\": \"juniper\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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Sightings

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  • 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.