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Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals | Critical CSS | Minify CSS | Defer CSS Javascript | CDN <= 3.21.2 — Authenticated (Subscriber+) Stored Cross-Site Scripting

CVE-2026-121763Published · Updated

Action summary

Affected: ≤3.21.2Update to 4.0.0 or newer

All remediation steps
Watch plugin
Severity
Medium6.4
CVSS
6.4
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
What does this vector mean?
AV:N Attack vector
Network
AC:L Attack complexity
Low
PR:L Privileges required
Low
UI:N User interaction
None
S:C Scope
Changed
C:L Confidentiality
Low
I:L Integrity
Low
A:N Availability
None
Weakness
CWE-79 Cross-Site Scripting
Required access
Unknown
Exploit prediction (EPSS)
No score
CISA KEV
Not listed
On this page8

Am I affected?

Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals | Critical CSS | Minify CSS | Defer CSS Javascript | CDN hummingbird-performance

  1. Affected≤ 3.21.2
  2. Patched in4.0.0

Update to 4.0.0 or newer.

You are affected if you run ≤ 3.21.2. Version 4.0.0 and later are not affected by this issue.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals | Critical CSS | Minify CSS | Defer CSS Javascript | CDN.
  • No admin access? Run a passive check of your site. It reads public files only.

What to do

  1. Update to version 4.0.0, or a newer patched version
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals | Critical CSS | Minify CSS | Defer CSS Javascript | CDN to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to mroccon.

The Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals | Critical CSS | Minify CSS | Defer CSS Javascript | CDN plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 3.21.2. This is due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

More in Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals | Critical CSS | Minify CSS | Defer CSS Javascript | CDN

All 9
More vulnerabilities in Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals | Critical CSS | Minify CSS | Defer CSS Javascript | CDN
SeverityVulnerabilityCVEPublished
Critical9.8Unauthenticated Remote Code Execution via Cookie Name in Page Cache Debug Log
≤3.21.0Update to 3.21.1
CVE-2026-83627
High7.2Authenticated (Administrator+) Remote Code Execution
<3.21.2Update to 3.21.2
CVE-2026-19224
High7.5Unauthenticated Sensitive Information Exposure via Log File
≤3.18.0Update to 3.18.1
CVE-2025-14437
Medium4.3Cross-Site Request Forgery
≤3.9.1Update to 3.9.2
CVE-2024-43117
Medium4.3Missing Authorization
≤3.9.1Update to 3.9.2
CVE-2024-43118

Same weakness (Cross-Site Scripting)

All Cross-Site Scripting
Other Cross-Site Scripting vulnerabilities
SeverityVulnerabilityCVEPublished
High7.2Unauthenticated Stored Cross-Site Scripting via Comment User-Agent Header
EZ SQL Reports Shortcode Widget and DB Backup≤5.25.25Update to 5.26.45
CVE-2026-120688
Critical9.8Unauthenticated Arbitrary File Upload via File Upload via Public Form Submission
Chatterbug Forms – Fast, Flexible WordPress Form Builder≤1.0.2Update to 1.1
CVE-2026-125055
Critical9.8Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter
ELEX WordPress HelpDesk & Customer Ticketing System≤3.3.9Update to 3.4.0
CVE-2026-119077
Medium5.3Unauthenticated Sensitive Information Exposure in 'search' Parameter
Customer Reviews for WooCommerce≤5.127.0Update to 5.128.0
CVE-2026-121518

Timeline

  1. CVE published

    Severity medium, CVSS 6.4

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. [object Object] Licensed under the CC BY-SA 4.0.
CVE® identifiers
[object Object]. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
CVSS / CWE
National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
VulnCrest content
Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.

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