CVE-2024-27891Network attack vector

Egress ACL policy bypass

Published Jun 4, 2026 · Updated Jun 4, 2026

Improper access control in Arista EOS 4.27.2F through 4.32.0.1F allows remote attackers to bypass egress ACL policy on 722XPM switches. Arista has not published the underlying implementation error; EOS can fail to enforce the configured allow-or-deny result for outbound packets. Exposure requires MACsec and egress ACLs on the same physical interface, with more than three MAC ACLs, seven IPv4 ACLs, or three IPv6 ACLs.

CVSS severity5.3
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Arista EOS 4.27.2F through 4.32.0.1F allows remote attackers to bypass egress ACL policy on 722XPM switches. Arista has not published the underlying implementation error; EOS can fail to enforce the configured allow-or-deny result for outbound packets. Exposure requires MACsec and egress ACLs on the same physical interface, with more than three MAC ACLs, seven IPv4 ACLs, or three IPv6 ACLs.

The record

CVE
CVE-2024-27891
Published
Jun 4, 2026
Updated
Jun 4, 2026
Vendor
Arista Networks
Product
Arista Extensible Operating System (EOS)
Classifications
CWE-284
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.27.2F <4.28.0
  2. Affected versionversion=4.28.0 <=4.28.10.1M
  3. Affected versionversion=4.29.0 <=4.29.7M
  4. Affected versionversion=4.30.0 <=4.30.6M
  5. Affected versionversion=4.31.0 <=4.31.2F
  6. Affected versionversion=4.32.0 <=4.32.0.1F

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Arista Networks · Arista Extensible Operating System (EOS)version=4.27.2F <4.28.0; version=4.28.0 <=4.28.10.1M; version=4.29.0 <=4.29.7M; version=4.30.0 <=4.30.6M; version=4.31.0 <=4.31.2F; version=4.32.0 <=4.32.0.1F

Published CVSS scores

6.9Arista NetworksCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
5.3Arista NetworksCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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