VPN Agent crash via out-of-bounds packet read
Published Nov 22, 2023 · Updated Jun 2, 2026
Out-of-bounds memory reads in Cisco Secure Client allow local users to crash the VPN Agent service with crafted packets to a local port. The client reads beyond a memory boundary while processing the crafted local packets, terminating the service. Exploitation requires valid credentials on a multi-user system while another user accesses the client, and the resulting crash interrupts VPN Agent service for every user.
Summary
What happened
Out-of-bounds memory reads in Cisco Secure Client allow local users to crash the VPN Agent service with crafted packets to a local port. The client reads beyond a memory boundary while processing the crafted local packets, terminating the service. Exploitation requires valid credentials on a multi-user system while another user accesses the client, and the resulting crash interrupts VPN Agent service for every user.
The record
- CVE
- CVE-2023-20240
- Published
- Nov 22, 2023
- Updated
- Jun 2, 2026
- Vendor
- ClamAV
- Product
- Cisco Secure Client
- Classifications
- CWE-125, T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 22, 2023CVE publishedPublication date reported by the CVE source.
- Jun 2, 2026Record 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.
- Affected versionversion=4.10.00093
- Affected versionversion=4.10.01075
- Affected versionversion=4.10.02086
- Affected versionversion=4.10.03104
- Affected versionversion=4.10.04065
- Affected versionversion=4.10.04071
- Affected versionversion=4.10.05085
- Affected versionversion=4.10.05095
- Affected versionversion=4.10.05111
- Affected versionversion=4.10.06079
- Affected versionversion=4.10.06090
- Affected versionversion=4.10.07061
- Affected versionversion=4.10.07062
- Affected versionversion=4.10.07073
- Affected versionversion=4.9.00086
- Affected versionversion=4.9.01095
- Affected versionversion=4.9.02028
- Affected versionversion=4.9.03047
- Affected versionversion=4.9.03049
- Affected versionversion=4.9.04043
- Affected versionversion=4.9.04053
- Affected versionversion=4.9.05042
- Affected versionversion=4.9.06037
- Affected versionversion=5.0.00238
- Affected versionversion=5.0.00529
- Affected versionversion=5.0.00556
- Affected versionversion=5.0.01242
- Affected versionversion=5.0.02075
- Affected versionversion=5.0.03072
- Affected versionversion=5.0.03076
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
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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