Policy bypass via misdetected encoded HTTP responses
Published Aug 3, 2023 · Updated Aug 2, 2024
Filter bypass in Cisco Secure Web Appliance scanning engines allows remote attackers to receive policy-blocked traffic via crafted HTTP responses. The engines fail to detect malicious traffic when an HTTP response uses the deflate, lzma, or brotli content-encoding format. Exploitation requires an affected encoding to be enabled and an appliance-mediated connection to a malicious server; the result is policy evasion, not code execution or appliance compromise.
Summary
What happened
Filter bypass in Cisco Secure Web Appliance scanning engines allows remote attackers to receive policy-blocked traffic via crafted HTTP responses. The engines fail to detect malicious traffic when an HTTP response uses the deflate, lzma, or brotli content-encoding format. Exploitation requires an affected encoding to be enabled and an appliance-mediated connection to a malicious server; the result is policy evasion, not code execution or appliance compromise.
The record
- CVE
- CVE-2023-20215
- Published
- Aug 3, 2023
- Updated
- Aug 2, 2024
- Vendor
- ClamAV
- Product
- Cisco Secure Web Appliance
- Classifications
- CWE-202, T1027
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 3, 2023CVE publishedPublication date reported by the CVE source.
- 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=11.7.0-406
- Affected versionversion=11.7.0-418
- Affected versionversion=11.7.1-006
- Affected versionversion=11.7.1-020
- Affected versionversion=11.7.1-049
- Affected versionversion=11.7.2-011
- Affected versionversion=11.8.0-414
- Affected versionversion=11.8.1-023
- Affected versionversion=11.8.3-018
- Affected versionversion=11.8.3-021
- Affected versionversion=12.0.1-268
- Affected versionversion=12.0.3-007
- Affected versionversion=12.5.1-011
- Affected versionversion=12.5.2-007
- Affected versionversion=12.5.4-005
- Affected versionversion=12.5.5-004
- Affected versionversion=14.0.2-012
- Affected versionversion=14.0.3-014
- Affected versionversion=14.0.4-005
- Affected versionversion=14.5.0-498
- Affected versionversion=14.5.1-016
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.
Weakness, pattern, technique
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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