CVE-2023-20057Network attack vector

URL reputation bypass via crafted URL processing

Published Jan 19, 2023 · Updated Aug 2, 2024

URL filter bypass in all Cisco AsyncOS releases for Cisco Email Security Appliance allows remote attackers to pass crafted malicious URLs. The URL filtering mechanism improperly processes specially crafted URLs, causing configured URL reputation filters to accept them. Exposure requires the Anti-Spam feature to be disabled and user interaction, but Cisco’s later investigation concluded that the issue is not exploitable.

CVSS severity0.0
None
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

URL filter bypass in all Cisco AsyncOS releases for Cisco Email Security Appliance allows remote attackers to pass crafted malicious URLs. The URL filtering mechanism improperly processes specially crafted URLs, causing configured URL reputation filters to accept them. Exposure requires the Anti-Spam feature to be disabled and user interaction, but Cisco’s later investigation concluded that the issue is not exploitable.

The record

CVE
CVE-2023-20057
Published
Jan 19, 2023
Updated
Aug 2, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-792, CWE-74
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 19, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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

0.0Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:N/E:X/RL:X/RC:X
6.5National Institute of Standards and TechnologyCVSS: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 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-792Incomplete Filtering of One or More Instances of Special Elements
CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

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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