CVE-2026-73438 (GCVE-0-2026-73438)
Vulnerability from cvelistv5 – Published: 2026-09-16 09:38 – Updated: 2026-09-16 10:13
VLAI
EPSS
VEX
Title
Security Advisory 0172
Summary
On affected platforms running Arista EOS with Open Shortest Path First version 3 (OSPFv3) configured, an unauthenticated attacker on the same OSPFv3 broadcast domain can send a specially crafted set of packets that can cause the Ospf3 agent to restart unexpectedly. The crash results in the loss of all OSPFv3 adjacencies on the affected device and may disrupt routing across the broader OSPF domain until the agent recovers.
This issue was reported externally by Dravanet Inc., and Arista is not aware of any malicious exploitation of this vulnerability in customer networks.
Severity
CWE
- CWE-617 - Reachable Assertion
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://www.arista.com/en/support/advisories-noti… | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Arista Networks | EOS |
Affected:
4.36.0F , ≤ 4.36.1F
(custom)
Affected: 4.35.0F , ≤ 4.35.5M (custom) Affected: 4.34.0F , ≤ 4.34.7M (custom) Affected: 4.33.0F , ≤ 4.33.9M (custom) Affected: 1.0.0 , < 4.33.0F (custom) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"platforms": [
"710 Series",
"720D Series",
"720XP/722XPM Series",
"750X Series",
"7010TX Series",
"7020R/R4 Series",
"7130 Series running EOS",
"7170 Series",
"7050X3/X4 Series",
"7060X/X2/X4/X5/X6 Series",
"7260X/X3 Series",
"7280R/R2/R3/R4 Series",
"7300X/X3 Series",
"7320X Series",
"7358X4 Series",
"7368X4 Series",
"7388X5 Series",
"7500R/R2/R3 Series",
"7800R3/R4 Series",
"7700R4 Series",
"AWE 5000 Series",
"AWE 7200R Series",
"CloudEOS",
"cEOS-lab",
"vEOS-lab",
"CloudVision eXchange, virtual or physical appliance"
],
"product": "EOS",
"vendor": "Arista Networks",
"versions": [
{
"lessThanOrEqual": "4.36.1F",
"status": "affected",
"version": "4.36.0F",
"versionType": "custom"
},
{
"lessThanOrEqual": "4.35.5M",
"status": "affected",
"version": "4.35.0F",
"versionType": "custom"
},
{
"lessThanOrEqual": "4.34.7M",
"status": "affected",
"version": "4.34.0F",
"versionType": "custom"
},
{
"lessThanOrEqual": "4.33.9M",
"status": "affected",
"version": "4.33.0F",
"versionType": "custom"
},
{
"lessThan": "4.33.0F",
"status": "affected",
"version": "1.0.0",
"versionType": "custom"
}
]
}
],
"configurations": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eIn order to be vulnerable to CVE-2026-73438, the following condition must be met:\u003c/p\u003e\u003cp\u003eOSPFv3 must be configured:\u003c/p\u003e\u003cpre\u003eswitch\u003eshow ospfv3\nOSPFv3 address-family ipv4\nRouting Process \u0026quot;ospfv3\u0026quot; with ID 10.1.1.5 and Instance 64 VRF default\n...\nOSPFv3 address-family ipv6\nRouting Process \u0026quot;ospfv3\u0026quot; with ID 10.1.1.5 and Instance 0 VRF default\n...\u003c/pre\u003e\u003cp\u003eor\u003c/p\u003e\u003cpre\u003eswitch\u003eshow ipv6 ospf\nRouting Process \u0026quot;ospfv3 0\u0026quot; with ID 10.1.1.5 and Instance 0 VRF default\n...\u003c/pre\u003e\u003cp\u003eIf the commands produce no output, then OSPFv3 is not configured:\u003c/p\u003e\u003cpre\u003eswitch\u003eshow ospfv3\nswitch\u003eshow ipv6 ospf\u003c/pre\u003e"
}
],
"value": "In order to be vulnerable to CVE-2026-73438, the following condition must be met:\n\nOSPFv3 must be configured:\n\n switch\u003eshow ospfv3\n OSPFv3 address-family ipv4\n Routing Process \"ospfv3\" with ID 10.1.1.5 and Instance 64 VRF default\n ...\n OSPFv3 address-family ipv6\n Routing Process \"ospfv3\" with ID 10.1.1.5 and Instance 0 VRF default\n ...\n\nor\n\n switch\u003eshow ipv6 ospf\n Routing Process \"ospfv3 0\" with ID 10.1.1.5 and Instance 0 VRF default\n ...\n\nIf the commands produce no output, then OSPFv3 is not configured:\n\n switch\u003eshow ospfv3\n switch\u003eshow ipv6 ospf"
}
],
"credits": [
{
"lang": "en",
"type": "reporter",
"value": "Dravanet Inc."
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eOn affected platforms running Arista EOS with Open Shortest Path First version 3 (OSPFv3) configured, an unauthenticated attacker on the same OSPFv3 broadcast domain can send a specially crafted set of packets that can cause the Ospf3 agent to restart unexpectedly. The crash results in the loss of all OSPFv3 adjacencies on the affected device and may disrupt routing across the broader OSPF domain until the agent recovers.\u003c/p\u003e\u003cp\u003eThis issue was reported externally by Dravanet Inc., and Arista is not aware of any malicious exploitation of this vulnerability in customer networks.\u003c/p\u003e"
}
],
"value": "On affected platforms running Arista EOS with Open Shortest Path First version 3 (OSPFv3) configured, an unauthenticated attacker on the same OSPFv3 broadcast domain can send a specially crafted set of packets that can cause the Ospf3 agent to restart unexpectedly. The crash results in the loss of all OSPFv3 adjacencies on the affected device and may disrupt routing across the broader OSPF domain until the agent recovers.\n\nThis issue was reported externally by Dravanet Inc., and Arista is not aware of any malicious exploitation of this vulnerability in customer networks."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
},
{
"cvssV4_0": {
"baseScore": 7,
"baseSeverity": "HIGH",
"vectorString": "CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H",
"version": "4.0"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-617",
"description": "CWE-617 Reachable Assertion",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-16T10:13:39.787Z",
"orgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
"shortName": "Arista"
},
"references": [
{
"name": "Security Advisory 0172",
"tags": [
"vendor-advisory"
],
"url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24728-security-advisory-0172"
}
],
"solutions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eThe recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below.\u003c/p\u003e\u003cp\u003eCVE-2026-73438 has been fixed in the following releases:\u003c/p\u003e\u003cul\u003e\u003cli\u003e4.36.2F and later releases in the 4.36.x train\u003c/li\u003e\u003cli\u003e4.35.6M and later releases in the 4.35.x train\u003c/li\u003e\u003cli\u003e4.34.8M and later releases in the 4.34.x train\u003c/li\u003e\u003cli\u003e4.33.10M and later releases in the 4.33.x train\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eNo hotfix is available for this issue.\u003c/p\u003e"
}
],
"value": "The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below.\n\nCVE-2026-73438 has been fixed in the following releases:\n- 4.36.2F and later releases in the 4.36.x train\n- 4.35.6M and later releases in the 4.35.x train\n- 4.34.8M and later releases in the 4.34.x train\n- 4.33.10M and later releases in the 4.33.x train\n\nNo hotfix is available for this issue."
}
],
"source": {
"advisory": "Security Advisory 0172",
"defects": [
"BUG 1876199"
],
"discovery": "EXTERNAL"
},
"title": "Security Advisory 0172",
"workarounds": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eThe OSPFv3 authentication feature helps to mitigate this vulnerability. OSPFv3 authentication prevents unauthorized actors from injecting crafted packets into the OSPF domain. Enabling it on all OSPFv3-speaking interfaces ensures that packets from unauthenticated senders are discarded before they can trigger this vulnerability.\u003c/p\u003e\u003cp\u003ePer-interface OSPFv3 encryption:\u003c/p\u003e\u003cp\u003eConfigure ESP-based encryption with authentication on each OSPFv3 interface. All peers on the same interface must use the same SPI, algorithm, and passphrase.\u003c/p\u003e\u003cpre\u003eswitch(config)# interface \u0026lt;interface-name\u0026gt;\nswitch(config-if)# ospfv3 encryption ipsec spi \u0026lt;spi-value\u0026gt; esp aes-256-cbc sha1 passphrase \u0026lt;shared-passphrase\u0026gt;\u003c/pre\u003e\u003cp\u003ePer-area OSPFv3 configuration:\u003c/p\u003e\u003cp\u003eConfigure ESP-based encryption with authentication on each OSPFv3 area.\u003c/p\u003e\u003cpre\u003eswitch(config)# router ospfv3\nswitch(config-router-ospfv3)# address-family ipv4\nswitch(config-router-ospfv3-af)# area \u0026lt;area-id\u0026gt; encryption ipsec spi \u0026lt;spi-value\u0026gt; esp aes-256-cbc sha1 passphrase \u0026lt;shared-passphrase\u0026gt;\nswitch(config-router-ospfv3-af)# address-family ipv6\nswitch(config-router-ospfv3-af)# area \u0026lt;area-id\u0026gt; encryption ipsec spi \u0026lt;spi-value\u0026gt; esp aes-256-cbc sha1 passphrase \u0026lt;shared-passphrase\u0026gt;\u003c/pre\u003e\u003cp\u003eCaution: Enabling OSPFv3 authentication must be coordinated across peering neighbors simultaneously. Applying this configuration to a single peer will temporarily break the routing adjacency, resulting in traffic disruption.\u003c/p\u003e"
}
],
"value": "The OSPFv3 authentication feature helps to mitigate this vulnerability. OSPFv3 authentication prevents unauthorized actors from injecting crafted packets into the OSPF domain. Enabling it on all OSPFv3-speaking interfaces ensures that packets from unauthenticated senders are discarded before they can trigger this vulnerability.\n\nPer-interface OSPFv3 encryption:\n\nConfigure ESP-based encryption with authentication on each OSPFv3 interface. All peers on the same interface must use the same SPI, algorithm, and passphrase.\n\n switch(config)# interface \u003cinterface-name\u003e\n switch(config-if)# ospfv3 encryption ipsec spi \u003cspi-value\u003e esp aes-256-cbc sha1 passphrase \u003cshared-passphrase\u003e\n\nPer-area OSPFv3 configuration:\n\nConfigure ESP-based encryption with authentication on each OSPFv3 area.\n\n switch(config)# router ospfv3\n switch(config-router-ospfv3)# address-family ipv4\n switch(config-router-ospfv3-af)# area \u003carea-id\u003e encryption ipsec spi \u003cspi-value\u003e esp aes-256-cbc sha1 passphrase \u003cshared-passphrase\u003e\n switch(config-router-ospfv3-af)# address-family ipv6\n switch(config-router-ospfv3-af)# area \u003carea-id\u003e encryption ipsec spi \u003cspi-value\u003e esp aes-256-cbc sha1 passphrase \u003cshared-passphrase\u003e\n\nCaution: Enabling OSPFv3 authentication must be coordinated across peering neighbors simultaneously. Applying this configuration to a single peer will temporarily break the routing adjacency, resulting in traffic disruption."
}
]
}
},
"cveMetadata": {
"assignerOrgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
"assignerShortName": "Arista",
"cveId": "CVE-2026-73438",
"datePublished": "2026-09-16T09:38:57.955Z",
"dateReserved": "2026-08-12T16:39:35.977Z",
"dateUpdated": "2026-09-16T10:13:39.787Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-73438\",\"sourceIdentifier\":\"psirt@arista.com\",\"published\":\"2026-09-16T10:16:51.690\",\"lastModified\":\"2026-09-16T10:16:51.690\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"On affected platforms running Arista EOS with Open Shortest Path First version 3 (OSPFv3) configured, an unauthenticated attacker on the same OSPFv3 broadcast domain can send a specially crafted set of packets that can cause the Ospf3 agent to restart unexpectedly. The crash results in the loss of all OSPFv3 adjacencies on the affected device and may disrupt routing across the broader OSPF domain until the agent recovers.\\n\\nThis issue was reported externally by Dravanet Inc., and Arista is not aware of any malicious exploitation of this vulnerability in customer networks.\"}],\"affected\":[{\"source\":\"psirt@arista.com\",\"affectedData\":[{\"vendor\":\"Arista Networks\",\"product\":\"EOS\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"4.36.0F\",\"lessThanOrEqual\":\"4.36.1F\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"4.35.0F\",\"lessThanOrEqual\":\"4.35.5M\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"4.34.0F\",\"lessThanOrEqual\":\"4.34.7M\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"4.33.0F\",\"lessThanOrEqual\":\"4.33.9M\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"1.0.0\",\"lessThan\":\"4.33.0F\",\"versionType\":\"custom\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":7.0,\"baseSeverity\":\"HIGH\",\"attackVector\":\"ADJACENT\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"HIGH\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"cvssMetricV31\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.6,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-617\"}]}],\"references\":[{\"url\":\"https://www.arista.com/en/support/advisories-notices/security-advisory/24728-security-advisory-0172\",\"source\":\"psirt@arista.com\"}]}}"
}
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
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.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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