CVE-2013-4090Network attack vector

Access-control bypass via false-negative ACL matching

Published Feb 12, 2020 · Updated Aug 6, 2024

Access-control failure in Varnish Cache before 3.0.4 allows remote attackers to trigger incorrect IP-based request-policy decisions. The VCL ACL compiler mishandles a single-host entry that overlaps a subnet entry, causing an address that should match the ACL to return a false negative. Reachability requires such an overlapping ACL and a request from the affected address; the VCL policy can then deny intended access or fail to apply a rule conditioned on a positive match.

CVSS severity7.5
High
EPSS probability1.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Access-control failure in Varnish Cache before 3.0.4 allows remote attackers to trigger incorrect IP-based request-policy decisions. The VCL ACL compiler mishandles a single-host entry that overlaps a subnet entry, causing an address that should match the ACL to return a false negative. Reachability requires such an overlapping ACL and a request from the affected address; the VCL policy can then deny intended access or fail to apply a rule conditioned on a positive match.

The record

CVE
CVE-2013-4090
Published
Feb 12, 2020
Updated
Aug 6, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 12, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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.

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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

T1190Exploit Public-Facing Application

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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