CVE-2022-20940Network attack vector

TLS session decryption via chosen-ciphertext oracle

Published Nov 10, 2022 · Updated Aug 3, 2024

Information disclosure in Cisco Firepower Threat Defense Software allows remote attackers to cryptanalyze previously captured TLS sessions. Its TLS handler responds observably differently to crafted TLS messages because Bleichenbacher countermeasures are implemented improperly, creating a chosen-ciphertext oracle. Exposure requires an active SSL decryption policy whose response to decryption errors is set to Block with reset, and the consequence is limited to disclosure of captured session contents.

CVSS severity5.3
Medium
EPSS probability0.69%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Cisco Firepower Threat Defense Software allows remote attackers to cryptanalyze previously captured TLS sessions. Its TLS handler responds observably differently to crafted TLS messages because Bleichenbacher countermeasures are implemented improperly, creating a chosen-ciphertext oracle. Exposure requires an active SSL decryption policy whose response to decryption errors is set to Block with reset, and the consequence is limited to disclosure of captured session contents.

The record

CVE
CVE-2022-20940
Published
Nov 10, 2022
Updated
Aug 3, 2024
Vendor
ClamAV
Product
Cisco Firepower Threat Defense Software
Classifications
CWE-203, T1040
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 10, 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

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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=6.2.3
  2. Affected versionversion=6.2.3.1
  3. Affected versionversion=6.2.3.10
  4. Affected versionversion=6.2.3.11
  5. Affected versionversion=6.2.3.12
  6. Affected versionversion=6.2.3.13
  7. Affected versionversion=6.2.3.14
  8. Affected versionversion=6.2.3.15
  9. Affected versionversion=6.2.3.16
  10. Affected versionversion=6.2.3.17
  11. Affected versionversion=6.2.3.18
  12. Affected versionversion=6.2.3.2
  13. Affected versionversion=6.2.3.3
  14. Affected versionversion=6.2.3.4
  15. Affected versionversion=6.2.3.5
  16. Affected versionversion=6.2.3.6
  17. Affected versionversion=6.2.3.7
  18. Affected versionversion=6.2.3.8
  19. Affected versionversion=6.2.3.9
  20. Affected versionversion=6.4.0
  21. Affected versionversion=6.4.0.1
  22. Affected versionversion=6.4.0.10
  23. Affected versionversion=6.4.0.11
  24. Affected versionversion=6.4.0.12
  25. Affected versionversion=6.4.0.13
  26. Affected versionversion=6.4.0.14
  27. Affected versionversion=6.4.0.2
  28. Affected versionversion=6.4.0.3
  29. Affected versionversion=6.4.0.4
  30. Affected versionversion=6.4.0.5
  31. Affected versionversion=6.4.0.6
  32. Affected versionversion=6.4.0.7
  33. Affected versionversion=6.4.0.8
  34. Affected versionversion=6.4.0.9
  35. Affected versionversion=6.6.0
  36. Affected versionversion=6.6.0.1
  37. Affected versionversion=6.6.1
  38. Affected versionversion=6.6.3
  39. Affected versionversion=6.6.4
  40. Affected versionversion=6.6.5
  41. Affected versionversion=6.6.5.1
  42. Affected versionversion=6.6.5.2
  43. Affected versionversion=6.7.0
  44. Affected versionversion=6.7.0.1
  45. Affected versionversion=6.7.0.2
  46. Affected versionversion=6.7.0.3
  47. Affected versionversion=7.0.0
  48. Affected versionversion=7.0.0.1
  49. Affected versionversion=7.0.1
  50. Affected versionversion=7.0.1.1
  51. Affected versionversion=7.0.2
  52. Affected versionversion=7.0.2.1
  53. Affected versionversion=7.0.3
  54. Affected versionversion=7.1.0
  55. Affected versionversion=7.1.0.1
  56. Affected versionversion=7.1.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Firepower Threat Defense Softwareversion=6.2.3; version=6.2.3.1; version=6.2.3.10; version=6.2.3.11; version=6.2.3.12; version=6.2.3.13; version=6.2.3.14; version=6.2.3.15; version=6.2.3.16; version=6.2.3.17; version=6.2.3.18; version=6.2.3.2; version=6.2.3.3; version=6.2.3.4; version=6.2.3.5; version=6.2.3.6; version=6.2.3.7; version=6.2.3.8; version=6.2.3.9; version=6.4.0; version=6.4.0.1; version=6.4.0.10; version=6.4.0.11; version=6.4.0.12; version=6.4.0.13; version=6.4.0.14; version=6.4.0.2; version=6.4.0.3; version=6.4.0.4; version=6.4.0.5; version=6.4.0.6; version=6.4.0.7; version=6.4.0.8; version=6.4.0.9; version=6.6.0; version=6.6.0.1; version=6.6.1; version=6.6.3; version=6.6.4; version=6.6.5; version=6.6.5.1; version=6.6.5.2; version=6.7.0; version=6.7.0.1; version=6.7.0.2; version=6.7.0.3; version=7.0.0; version=7.0.0.1; version=7.0.1; version=7.0.1.1; version=7.0.2; version=7.0.2.1; version=7.0.3; version=7.1.0; version=7.1.0.1; version=7.1.0.2

Published CVSS scores

5.3Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 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

CWE-203Observable Discrepancy
T1040Network Sniffing

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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