CVE-2021-45468: Imperva Web Application Firewall (WAF) before 2021-12-23 allows remote unauthenticated attackers to use "Conte

Q: How do I fix CVE-2021-45468?

web application firewall: upgrade to 2021-12-23. Exact commands for each OS are on this page.

Q: Is CVE-2021-45468 being exploited?

CVE-2021-45468 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-45468 affect?

CVE-2021-45468 affects web application firewall. Severity is critical (CVSS 9.8). Imperva Web Application Firewall (WAF) before 2021-12-23 allows remote unauthenticated attackers to use "Content-Encoding: gzip" to evade WAF security controls and send malicious HTTP POST requests to web servers behind the WAF.

Q: How urgent is CVE-2021-45468?

Priority 67/100. Critical severity; EPSS top 9%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-45468 is a critical-severity flaw (CVSS 9.8) affecting web application firewall. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Imperva Web Application Firewall (WAF) before 2021-12-23 allows remote unauthenticated attackers to use "Content-Encoding: gzip" to evade WAF security controls and send malicious HTTP POST requests to web servers behind the WAF.

Why this priority

Critical severity
EPSS top 9%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	4.0% (top 9%)
CISA exploited list	No
Weakness	CWE-444
Published	2022-01-14
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: imperva

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-01-14 18:15 UTCPublished CVE record published
2026-06-17 04:13 UTCUpdated Record last modified

imperva web application firewall UPGRADE

Affected: < 2021-12-23

Fixed in: 2021-12-23

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy web-application-firewall || rpm -q web-application-firewall || web-application-firewall --version

2. UPGRADE to 2021-12-23 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade web-application-firewall

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade web-application-firewall

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-45468?

web application firewall: upgrade to 2021-12-23. Exact commands for each OS are on this page.

Is CVE-2021-45468 being exploited?

CVE-2021-45468 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-45468 affect?

CVE-2021-45468 affects web application firewall. Severity is critical (CVSS 9.8). Imperva Web Application Firewall (WAF) before 2021-12-23 allows remote unauthenticated attackers to use "Content-Encoding: gzip" to evade WAF security controls and send malicious HTTP POST requests to web servers behind the WAF.

How urgent is CVE-2021-45468?

Priority 67/100. Critical severity; EPSS top 9%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

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References

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