On affected platforms running Arista EOS with IS-IS configured, an unauthenticated attacker who can inject a specially crafted IS-IS LSP PDU can cause the legitimate LSP to be unexpectedly purged from the IS-IS link-state database. This may result in traffic loss.
" } ] } ], "references": [ { "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24716-security-advisory-0160", "name": "Security Advisory 0160", "tags": [ "vendor-advisory" ] } ], "metrics": [ { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV3_1": { "version": "3.1", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "baseSeverity": "HIGH", "baseScore": 7.4, "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H" } }, { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV4_0": { "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "HIGH", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 7, "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" } } ], "configurations": [ { "lang": "en", "value": "In order to be vulnerable to CVE-2026-73459, the following condition must be met: \n\nIS-IS should be configured.\n\n\n\nswitch# show isis summary\nIS-IS Instance: 1 VRF: default\n Instance ID: 0\n System ID: 1111.1111.1001, administratively enabled\n Router ID: IPv4: 0.0.0.0\n Multi Topology disabled, not attached\n IPv4 Preference: Level 1: 115, Level 2: 115\n IPv6 Preference: Level 1: 115, Level 2: 115\n IS-Type: Level 1 and 2, Number active interfaces: 1\n Routes both IPv4 and IPv6\n LSP size maximum: Level 1: 1492, Level 2: 1492\n Interval Type Max Wait Initial Wait Hold Interval\n ----------------------- -------- ------------ -------------\n LSP generation interval 5 s 50 ms 50 ms\n SPF interval 30000 ms 300 ms 80 ms\n Current SPF hold interval(ms): Level 1: 80, Level 2: 80\n Last Level 1 SPF run 9 seconds ago\n Last Level 2 SPF run 9 seconds ago\n CSNP generation interval: 10 seconds\n Dynamic Flooding: Disabled\n Authentication mode: Level 1: None, Level 2: None\n Graceful Restart: Disabled, Graceful Restart Helper: Enabled\n Area addresses: 40\n level 1: number DIS interfaces: 0, LSDB size: 1\n Area Leader: None\n Overload Bit is not set. \n level 2: number DIS interfaces: 0, LSDB size: 1\n Area Leader: None\n Overload Bit is not set. \n Redistributed Level 1 routes: 0 limit: Not Configured\n Redistributed Level 2 routes: 0 limit: Not Configured\n\n\n\nIf IS-IS is not configured, there is no exposure to this issue.\n\n\n\n\nswitch#show isis summary\nswitch#", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "In order to be vulnerable to CVE-2026-73459, the following condition must be met:
IS-IS should be configured.
switch# show isis summary\nIS-IS Instance: 1 VRF: default\n Instance ID: 0\n System ID: 1111.1111.1001, administratively enabled\n Router ID: IPv4: 0.0.0.0\n Multi Topology disabled, not attached\n IPv4 Preference: Level 1: 115, Level 2: 115\n IPv6 Preference: Level 1: 115, Level 2: 115\n IS-Type: Level 1 and 2, Number active interfaces: 1\n Routes both IPv4 and IPv6\n LSP size maximum: Level 1: 1492, Level 2: 1492\n Interval Type Max Wait Initial Wait Hold Interval\n ----------------------- -------- ------------ -------------\n LSP generation interval 5 s 50 ms 50 ms\n SPF interval 30000 ms 300 ms 80 ms\n Current SPF hold interval(ms): Level 1: 80, Level 2: 80\n Last Level 1 SPF run 9 seconds ago\n Last Level 2 SPF run 9 seconds ago\n CSNP generation interval: 10 seconds\n Dynamic Flooding: Disabled\n Authentication mode: Level 1: None, Level 2: None\n Graceful Restart: Disabled, Graceful Restart Helper: Enabled\n Area addresses: 40\n level 1: number DIS interfaces: 0, LSDB size: 1\n Area Leader: None\n Overload Bit is not set. \n level 2: number DIS interfaces: 0, LSDB size: 1\n Area Leader: None\n Overload Bit is not set. \n Redistributed Level 1 routes: 0 limit: Not Configured\n Redistributed Level 2 routes: 0 limit: Not Configured
If IS-IS is not configured, there is no exposure to this issue.
switch#show isis summary\nswitch#" } ] } ], "workarounds": [ { "lang": "en", "value": "No workaround is available for this issue.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "
No workaround is available for this issue.
" } ] } ], "solutions": [ { "lang": "en", "value": "The recommended resolution is to upgrade to a fixed software version.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "The recommended resolution is to upgrade to a fixed software version.
" } ] } ], "credits": [ { "lang": "en", "value": "This issue was discovered internally by Arista and the company is not aware of any malicious uses of these issues in customer networks.", "type": "finder" } ], "source": { "advisory": "0160", "discovery": "UNKNOWN", "defects": [ "BUG1840507" ] }, "x_generator": { "engine": "Vulnogram 1.0.5" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-09-16T19:34:28.975379Z", "id": "CVE-2026-73459", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-16T19:34:44.583Z" } } ] } }