CVE-2023-27595Network attack vector

Network policy bypass via overbroad filter cleanup

Published Mar 17, 2023 · Updated Feb 25, 2025

Network policy bypass in Cilium 1.13.0 allows remote attackers to reach protected endpoints during an agent restart. The init.sh cleanup removes ingress and egress tc filters from host interfaces whose filter names lack “cilium,” and lxc programs remain absent until endpoint regeneration. Exploitation requires traffic to arrive during this transient restart window; affected connections can bypass policy enforcement or lose load balancing.

CVSS severity6.5
Medium
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Network policy bypass in Cilium 1.13.0 allows remote attackers to reach protected endpoints during an agent restart. The init.sh cleanup removes ingress and egress tc filters from host interfaces whose filter names lack “cilium,” and lxc programs remain absent until endpoint regeneration. Exploitation requires traffic to arrive during this transient restart window; affected connections can bypass policy enforcement or lose load balancing.

The record

CVE
CVE-2023-27595
Published
Mar 17, 2023
Updated
Feb 25, 2025
Vendor
Cilium
Product
Cilium
Classifications
CWE-755
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 25, 2025Record 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== 1.13.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cilium · Ciliumversion== 1.13.0

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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