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PatchSiren cyber security CVE debrief

CVE-2024-27891 Arista Networks CVE debrief

On affected platforms running Arista EOS with MACsec and egress ACLs configured on the same interfaces, the ACL policies may not be enforced for packets egressing on those ports. This can cause outgoing packets to incorrectly be allowed or denied.

Vendor
Arista Networks
Product
EOS
CVSS
MEDIUM 6.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-04
Original CVE updated
2026-07-22
Advisory published
2026-06-04
Advisory updated
2026-07-22

Who should care

Users of Arista EOS with MACsec and egress ACLs configured on the same interfaces should review and apply patches as necessary.

Technical summary

The vulnerability has a CVSS score of 6.9 and is classified as MEDIUM severity. The CVSS vector is CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/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.

Defensive priority

MEDIUM

Recommended defensive actions

  • Review and apply patches as necessary.
  • Refer to the Arista security advisory for more information: [ref-4](https://www.arista.com/en/support/advisories-notices/security-advisory/19908-security-advisory-0102).

Evidence notes

The vendor is identified as Arista based on evidence from the source item.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-27891 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-27891

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2024-27891 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-27891

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://www.arista.com/en/support/advisories-notices/security-advisory/19908-security-advisory-0102

    [email protected]

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.