CVE-2021-45468Public exploitNetwork attack vector

Unauthenticated WAF bypass via gzip header prefix

Published Jan 14, 2022 · Updated Aug 4, 2024

Security control bypass in Imperva Cloud WAF before 2021-12-23 allows remote attackers to send uninspected malicious HTTP POST requests. Its POST-processing path accepts any Content-Encoding value beginning with gzip and skips rule inspection even when the body remains uncompressed. No authentication or user interaction is required, and the bypass can deliver backend-specific exploits that the WAF would otherwise block.

CVSS severity9.8
Critical
EPSS probability3.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Security control bypass in Imperva Cloud WAF before 2021-12-23 allows remote attackers to send uninspected malicious HTTP POST requests. Its POST-processing path accepts any Content-Encoding value beginning with gzip and skips rule inspection even when the body remains uncompressed. No authentication or user interaction is required, and the bypass can deliver backend-specific exploits that the WAF would otherwise block.

The record

CVE
CVE-2021-45468
Published
Jan 14, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-444, CAPEC-273, CAPEC-33, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CAPEC-273HTTP Response Smuggling
CAPEC-33HTTP Request Smuggling
T1190Exploit Public-Facing Application

Public exploit references

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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