240 lines
15 KiB
JSON
240 lines
15 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-77191",
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"assignerOrgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
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"state": "PUBLISHED",
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"assignerShortName": "Arista",
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"dateReserved": "2026-08-20T16:41:22.053Z",
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"datePublished": "2026-09-14T22:06:28.153Z",
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"dateUpdated": "2026-09-15T13:41:05.782Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
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"shortName": "Arista",
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"dateUpdated": "2026-09-14T22:06:28.153Z"
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},
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"title": "All of the CVEs covered in this advisory apply to affected platforms running Arista EOS with 802.1X authentication and authorization enabled and Access Control Lists (ACLs) configured for per-supplicant policy enforcement. An authenticated supplicant on an",
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"datePublic": "2026-09-09T22:02:00.000Z",
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"problemTypes": [
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{
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"descriptions": [
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{
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"lang": "en",
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"cweId": "CWE-862",
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"description": "CWE-862 Missing Authorization",
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"type": "CWE"
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}
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]
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}
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],
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"impacts": [
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{
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"capecId": "CAPEC-180",
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"descriptions": [
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{
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"lang": "en",
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"value": "CAPEC-180 Exploiting Incorrectly Configured Access Control Security Levels"
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}
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]
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}
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],
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"affected": [
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{
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"vendor": "Arista Networks",
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"product": "EOS",
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"versions": [
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{
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"status": "affected",
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"version": "4.35.0",
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"lessThanOrEqual": "4.35.0.3F",
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"versionType": "custom"
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},
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{
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"status": "affected",
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"version": "4.34.0",
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"lessThanOrEqual": "4.34.5M",
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"versionType": "custom"
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},
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{
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"status": "affected",
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"version": "0.0.0",
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"lessThanOrEqual": "4.33.7.1M",
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"versionType": "custom"
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}
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],
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"defaultStatus": "unaffected"
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}
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],
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"descriptions": [
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{
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"lang": "en",
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"value": "An authenticated supplicant on an adjacent network may bypass intended network authorization policy and send unrestricted traffic during a brief window (milliseconds to seconds) between the completion of the authentication phase and the full enforcement of its assigned ACL.",
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"value": "<pre>An authenticated supplicant on an adjacent network may bypass intended network authorization policy and send unrestricted traffic during a brief window (milliseconds to seconds) between the completion of the authentication phase and the full enforcement of its assigned ACL.\n</pre>"
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}
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]
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}
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],
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"references": [
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{
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"url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24706-security-advisory-0150"
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}
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],
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"configurations": [
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{
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"lang": "en",
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"value": "In order to be vulnerable to any of the vulnerabilities, the following condition must be met under interface configuration mode:\n\n * 802.1X (dot1x in the CLI) must be configured with pae authenticator \n\n\n * port-control must be set to auto mode \n\n\n * A static or dynamic ACL must be configured. \n\n\n * The RADIUS Access-Accept or Change-of-Authorization (CoA) assigns an ACL to that supplicant using RADIUS AVP (Attribute-Value pair) Filter-Id or NAS-Filter-Rule\n \n\n\n\nBelow is an example of one configuration. Note that “mac based authentication always” is optional The supplicant can authenticate with either EAPOL or MBA.\n\n\n\nswitch(config-if-et1)#show active\n \ninterface Ethernet5\n switchport mode trunk\n spanning-tree portfast edge\n dot1x pae authenticator\n dot1x port-control auto\n \ndot1x system-auth-control\n\n\n \n\n\n\nIn this example port control is in “auto” mode, necessary for the condition to occur.\n\n\n\nconfig)#show dot1x interface ethernet 5 details\nDot1X Information for Ethernet5\n--------------------------------------------\nPort control: auto\nForced phone authorization: disabled\nEAPOL: enabled\nHost mode: multi-host\nMAC-based authentication: enabled\nMAC-based authentication host mode: Unconfigured\nMAC-based authentication always: enabled\nQuiet period: 60 seconds\nTX period: 5 seconds\nMaximum reauth requests: 2\nIgnore reauth timeout: No\nAuth failure VLAN: Unconfigured\nUnauthorized access VLAN egress: No\nUnauthorized native VLAN egress: No\nEAPOL authentication failure fallback: Unconfigured\nPort ErrDisabled by CoA: no\n \nDot1X Authenticator Client\n\n\n \n\n\n\n Use a preconfigured ACL with which the RADIUS server returns in the Filter-Id AVP\n\n\n\nswitch(config)#ip access-list EMPLOYEE-ACL\nswitch(config-ip-acl-EMPLOYEE-ACL)#10 permit ip 10.0.0.0/8 any\nswitch(config-ip-acl-EMPLOYEE-ACL)#20 deny ip any any\n\n\n \n\n\n\nAAA server will return the ACL name through Filter-Id AVP through Access-Accept or CoA messages , in the above sample , Filter-Id AVP with EMPLOYEE-ACL will be received from the server.\n\n\n\nTo verify the configured ACL, execute the following show command to identify the ACL applied to the interface:\n\n\n\nswitch(config)#show ip access-lists interface Ethernet5 summary \nIP Access List EMPLOYEE-ACL\n 10 permit ip 10.0.0.0/8 any\n 20 deny ip any any\n \n Total rules configured: 2\n Configured on Ingress: Ethernet5\n Active on Ingress: Ethernet5",
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"value": "<pre><p>In order to be vulnerable to any of the vulnerabilities, the following condition must be met under interface configuration mode:</p><ol><li>802.1X (dot1x in the CLI) must be configured with <b>pae authenticator</b><div> </div></li><li>port-control must be set to auto mode<div> </div></li><li>A static or dynamic ACL must be configured.<div> </div></li><li>The RADIUS Access-Accept or Change-of-Authorization (CoA) assigns an ACL to that supplicant using RADIUS AVP (Attribute-Value pair) Filter-Id or NAS-Filter-Rule</li></ol><div> </div><p>Below is an example of one configuration. Note that “mac based authentication always” is optional The supplicant can authenticate with either EAPOL or MBA.</p><pre>switch(config-if-et1)#show active\n \ninterface Ethernet5\n switchport mode trunk\n spanning-tree portfast edge\n dot1x pae authenticator\n dot1x port-control auto\n \ndot1x system-auth-control\n</pre><div> </div><p>In this example port control is in “auto” mode, necessary for the condition to occur.</p><pre>config)#show dot1x interface ethernet 5 details\nDot1X Information for Ethernet5\n--------------------------------------------\nPort control: auto\nForced phone authorization: disabled\nEAPOL: enabled\nHost mode: multi-host\nMAC-based authentication: enabled\nMAC-based authentication host mode: Unconfigured\nMAC-based authentication always: enabled\nQuiet period: 60 seconds\nTX period: 5 seconds\nMaximum reauth requests: 2\nIgnore reauth timeout: No\nAuth failure VLAN: Unconfigured\nUnauthorized access VLAN egress: No\nUnauthorized native VLAN egress: No\nEAPOL authentication failure fallback: Unconfigured\nPort ErrDisabled by CoA: no\n \nDot1X Authenticator Client\n</pre><div> </div><p> Use a preconfigured ACL with which the RADIUS server returns in the <b>Filter-Id</b> AVP</p><pre>switch(config)#ip access-list EMPLOYEE-ACL\nswitch(config-ip-acl-EMPLOYEE-ACL)#10 permit ip 10.0.0.0/8 any\nswitch(config-ip-acl-EMPLOYEE-ACL)#20 deny ip any any\n</pre><div> </div><p>AAA server will return the ACL name through <b>Filter-Id</b> AVP through Access-Accept or CoA messages , in the above sample , Filter-Id AVP with EMPLOYEE-ACL will be received from the server.</p><p>To verify the configured ACL, execute the following show command to identify the ACL applied to the interface:</p><pre>switch(config)#show ip access-lists interface Ethernet5 summary \nIP Access List EMPLOYEE-ACL\n 10 permit ip 10.0.0.0/8 any\n 20 deny ip any any\n \n Total rules configured: 2\n Configured on Ingress: Ethernet5\n Active on Ingress: Ethernet5 </pre></pre>"
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}
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]
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}
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],
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"workarounds": [
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{
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"lang": "en",
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"value": "There is no workaround available for CVE-2026-77191.",
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"value": "<pre>\nThere is no workaround available for CVE-2026-77191.\n</pre>"
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}
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]
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}
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],
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"solutions": [
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{
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"lang": "en",
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"value": "CVE-2026-77191 has been fixed in the following releases:\n* 4.35.1F and later releases in the 4.35.x train.\n* 4.34.6M and later releases in the 4.34.x train.\n* 4.33.8M and later releases in the 4.33.x train.",
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"value": "<pre>\nCVE-2026-77191 has been fixed in the following releases:\n* 4.35.1F and later releases in the 4.35.x train.\n* 4.34.6M and later releases in the 4.34.x train.\n* 4.33.8M and later releases in the 4.33.x train.\n</pre>"
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}
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]
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}
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],
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"credits": [
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{
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"lang": "en",
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"value": "Those issues were discovered internally by Arista, and the company is not aware of any malicious exploitation of these vulnerabilities in customer networks.",
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"type": "finder"
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}
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],
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"source": {
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"advisory": "150",
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"discovery": "INTERNAL",
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"defects": [
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"BUG 1108416"
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]
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},
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"x_generator": {
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"engine": "Vulnogram 1.0.5"
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},
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"metrics": [
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"format": "CVSS",
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"value": "GENERAL"
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],
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"cvssV3_1": {
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"version": "3.1",
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"attackVector": "ADJACENT_NETWORK",
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"attackComplexity": "HIGH",
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"privilegesRequired": "LOW",
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"userInteraction": "NONE",
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"scope": "UNCHANGED",
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"confidentialityImpact": "NONE",
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"integrityImpact": "LOW",
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"availabilityImpact": "NONE",
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"baseSeverity": "LOW",
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"baseScore": 2.6,
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"vectorString": "CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N"
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"attackRequirements": "PRESENT",
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"vulnConfidentialityImpact": "NONE",
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"subConfidentialityImpact": "NONE",
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"vulnIntegrityImpact": "LOW",
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"subIntegrityImpact": "NONE",
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"vulnAvailabilityImpact": "NONE",
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"subAvailabilityImpact": "NONE",
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"exploitMaturity": "NOT_DEFINED",
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"Safety": "NOT_DEFINED",
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"Automatable": "NOT_DEFINED",
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"Recovery": "NOT_DEFINED",
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"valueDensity": "NOT_DEFINED",
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"vulnerabilityResponseEffort": "NOT_DEFINED",
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"providerUrgency": "NOT_DEFINED",
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"version": "4.0",
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"baseSeverity": "LOW",
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"type": "ssvc",
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"content": {
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"timestamp": "2026-09-15T13:40:55.120355Z",
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"id": "CVE-2026-77191",
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"options": [
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{
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"Automatable": "no"
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"version": "2.0.3"
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],
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"title": "CISA ADP Vulnrichment",
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"dateUpdated": "2026-09-15T13:41:05.782Z"
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