CVE-2026-121290
Security Advisory 0209
On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its default value disables default protective Access Control List (ACL) rules against unexpected BGP peering attempts.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Security Advisory 0209
On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its default value disables default protective Access Control List (ACL) rules against unexpected BGP peering attempts.
- Record
CVE-2026-121290- CVSS 4.0
- 8.3 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Weakness
- CWE-420
- Updated
- 2026-11-10
EUVDEUVD-2026-122811
On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its default value disables default protective Access Control List (ACL) rules against unexpected BGP peering attempts.
- Record
EUVD-2026-122811- CVSS 4.0
- 8.3 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-11
GitHub AdvisoriesGHSA-vj6p-mj5m-9j2q
On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP...
On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its default value disables default protective Access Control List (ACL) rules against unexpected BGP peering attempts.
- Record
GHSA-vj6p-mj5m-9j2q- CVSS 4.0
- 8.3 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/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 - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Weakness
- CWE-420
- Updated
- 2026-11-10
NVD
On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its default value disables default protective Access Control List (ACL) rules against unexpected BGP peering attempts.
- Record
CVE-2026-121290- CVSS 4.0
- 8.3 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/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 - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H - Weakness
- CWE-420
- Updated
- 2026-11-10
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| published | EUVD | |
| published | EUVD | |
| references, severity, title | CVE List, NVD | |
| aliases, cwes, references, severity, title | GitHub Advisories | |
| first indexed | EUVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-121290 is a high vulnerability (CVSS 8.3) in Arista Networks Eos, published November 10, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.36%, the 29th percentile. No source names a fixed version.