CVE-2022-20960Network attack vector

Email delivery interruption via concurrent TLS connections

Published Nov 3, 2022 · Updated Aug 3, 2024

Resource exhaustion in specified Cisco Secure Email AsyncOS releases allows remote attackers to interrupt inbound email delivery over TLS. The appliance improperly handles many concurrent TLS connections, exhausts connection capacity, and drops new TLS email messages. No authentication or user interaction is required; the appliance does not reload and recovers within hours after the connection flood stops.

CVSS severity7.5
High
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in specified Cisco Secure Email AsyncOS releases allows remote attackers to interrupt inbound email delivery over TLS. The appliance improperly handles many concurrent TLS connections, exhausts connection capacity, and drops new TLS email messages. No authentication or user interaction is required; the appliance does not reload and recovers within hours after the connection flood stops.

The record

CVE
CVE-2022-20960
Published
Nov 3, 2022
Updated
Aug 3, 2024
Vendor
ClamAV
Product
Cisco Secure Email
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 3, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=11.0.3-238
  2. Affected versionversion=11.1.0-069
  3. Affected versionversion=11.1.0-128
  4. Affected versionversion=11.1.0-131
  5. Affected versionversion=12.0.0-419
  6. Affected versionversion=12.1.0-071
  7. Affected versionversion=12.1.0-087
  8. Affected versionversion=12.1.0-089
  9. Affected versionversion=12.5.0-066
  10. Affected versionversion=13.0.0-392
  11. Affected versionversion=13.5.1-277
  12. Affected versionversion=14.0.0-698
  13. Affected versionversion=14.2.0-620

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Secure Emailversion=11.0.3-238; version=11.1.0-069; version=11.1.0-128; version=11.1.0-131; version=12.0.0-419; version=12.1.0-071; version=12.1.0-087; version=12.1.0-089; version=12.5.0-066; version=13.0.0-392; version=13.5.1-277; version=14.0.0-698; version=14.2.0-620

Published CVSS scores

7.5Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:X/RL:X/RC:X

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-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

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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