CVE-2020-3285Network attack vector

Unauthenticated URL filtering bypass via Snort logic error

Published May 6, 2020 · Updated Nov 15, 2024

Policy bypass in Cisco Firepower Threat Defense 6.4.0 through 6.4.0.8 allows remote attackers to reach blocked URLs over TLS 1.3. Snort's TLS 1.3 connection-handling logic fails to apply the configured URL-category block policy to crafted TLS 1.3 connections. The device must use both TLS 1.3 policy and URL-category blocking; unauthenticated exploitation permits access to normally dropped URLs without exposing or changing device data.

CVSS severity5.8
Medium
EPSS probability1.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Policy bypass in Cisco Firepower Threat Defense 6.4.0 through 6.4.0.8 allows remote attackers to reach blocked URLs over TLS 1.3. Snort's TLS 1.3 connection-handling logic fails to apply the configured URL-category block policy to crafted TLS 1.3 connections. The device must use both TLS 1.3 policy and URL-category blocking; unauthenticated exploitation permits access to normally dropped URLs without exposing or changing device data.

The record

CVE
CVE-2020-3285
Published
May 6, 2020
Updated
Nov 15, 2024
Vendor
ClamAV
Product
Cisco Firepower Threat Defense
Classifications
CWE-693
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2020CVE publishedPublication date reported by the CVE source.
  2. Nov 15, 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?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Firepower Threat Defenseversion=n/a

Published CVSS scores

5.8Cisco Systems, Inc.CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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.

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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-693Protection Mechanism Failure

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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