CVE-2024-20337Network attack vector

SAML token theft via CRLF injection

Published Mar 6, 2024 · Updated Aug 1, 2024

CRLF injection in Cisco Secure Client allows remote attackers to steal SAML tokens or execute browser scripts through a crafted link. The SAML authentication flow insufficiently validates user-controlled link input, allowing CRLF sequences to alter data handled by the external browser. Exploitation requires a user to click the link while establishing a VPN session through a headend configured for SAML External Browser; a stolen token grants the user's VPN privileges, while protected hosts still require additional credentials.

CVSS severity8.2
High
EPSS probability29.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CRLF injection in Cisco Secure Client allows remote attackers to steal SAML tokens or execute browser scripts through a crafted link. The SAML authentication flow insufficiently validates user-controlled link input, allowing CRLF sequences to alter data handled by the external browser. Exploitation requires a user to click the link while establishing a VPN session through a headend configured for SAML External Browser; a stolen token grants the user's VPN privileges, while protected hosts still require additional credentials.

The record

CVE
CVE-2024-20337
Published
Mar 6, 2024
Updated
Aug 1, 2024
Vendor
ClamAV
Product
Cisco Secure Client
Classifications
CWE-93, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 6, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 1, 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=4.10.00093
  2. Affected versionversion=4.10.01075
  3. Affected versionversion=4.10.02086
  4. Affected versionversion=4.10.03104
  5. Affected versionversion=4.10.04065
  6. Affected versionversion=4.10.04071
  7. Affected versionversion=4.10.05085
  8. Affected versionversion=4.10.05095
  9. Affected versionversion=4.10.05111
  10. Affected versionversion=4.10.06079
  11. Affected versionversion=4.10.06090
  12. Affected versionversion=4.10.07061
  13. Affected versionversion=4.10.07062
  14. Affected versionversion=4.10.07073
  15. Affected versionversion=4.9.00086
  16. Affected versionversion=4.9.01095
  17. Affected versionversion=4.9.02028
  18. Affected versionversion=4.9.03047
  19. Affected versionversion=4.9.03049
  20. Affected versionversion=4.9.04043
  21. Affected versionversion=4.9.04053
  22. Affected versionversion=4.9.05042
  23. Affected versionversion=4.9.06037
  24. Affected versionversion=5.0.00238
  25. Affected versionversion=5.0.00529
  26. Affected versionversion=5.0.00556
  27. Affected versionversion=5.0.01242
  28. Affected versionversion=5.0.02075
  29. Affected versionversion=5.0.03072
  30. Affected versionversion=5.0.03076
  31. Affected versionversion=5.0.04032
  32. Affected versionversion=5.0.05040
  33. Affected versionversion=5.1.0.136
  34. Affected versionversion=5.1.1.42

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Secure Clientversion=4.10.00093; version=4.10.01075; version=4.10.02086; version=4.10.03104; version=4.10.04065; version=4.10.04071; version=4.10.05085; version=4.10.05095; version=4.10.05111; version=4.10.06079; version=4.10.06090; version=4.10.07061; version=4.10.07062; version=4.10.07073; version=4.9.00086; version=4.9.01095; version=4.9.02028; version=4.9.03047; version=4.9.03049; version=4.9.04043; version=4.9.04053; version=4.9.05042; version=4.9.06037; version=5.0.00238; version=5.0.00529; version=5.0.00556; version=5.0.01242; version=5.0.02075; version=5.0.03072; version=5.0.03076; version=5.0.04032; version=5.0.05040; version=5.1.0.136; version=5.1.1.42

Published CVSS scores

8.2CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N/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 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-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
T1189Drive-by Compromise

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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