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.
PUBLISHED5.2CWE-354
Security Advisory 0160
Problem type
Affected products
Arista Networks
EOS
<= 4.36.1F - AFFECTED
References
GitHub Security Advisories
GHSA-vq63-cff6-37q2
On affected platforms running Arista EOS with IS-IS configured, an unauthenticated attacker who...
https://github.com/advisories/GHSA-vq63-cff6-37q2On 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.
JSON source
https://cveawg.mitre.org/api/cve/CVE-2026-73459Click to expand
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"assignerShortName": "Arista",
"dateUpdated": "2026-09-15T23:16:27.270Z",
"dateReserved": "2026-08-12T16:45:03.511Z",
"datePublished": "2026-09-15T23:16:27.270Z",
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"title": "Security Advisory 0160",
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"value": "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.",
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"affected": [
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"product": "EOS",
"defaultStatus": "unaffected",
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"description": "CWE-354: Improper Validation of Integrity Check Value",
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"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#",
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"value": "<p>In order to be vulnerable to CVE-2026-73459, the following condition must be met: <br><br>IS-IS should be configured.</p><pre>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</pre><p>If IS-IS is not configured, there is no exposure to this issue.<br></p><pre>switch#show isis summary\nswitch# </pre>"
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"value": "This issue was discovered internally by Arista and the company is not aware of any malicious uses of these issues in customer networks.",
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