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ToTop Link <= 1.7.1 — Unauthenticated PHP Object Injection

CVE-2021-24857Published · Updated

Action summary

Affected: ≤1.7.1No patch available

What to do until a fix ships
Severity
Critical9.0
CVSS
9.0
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
What does this vector mean?
AV:N Attack vector
Network
AC:H Attack complexity
High
PR:N Privileges required
None
UI:N User interaction
None
S:C Scope
Changed
C:H Confidentiality
High
I:H Integrity
High
A:H Availability
High
Weakness
CWE-502 PHP Object Injection
Required access
No account needed
Exploit prediction (EPSS)
No score
CISA KEV
Not listed

Am I affected?

ToTop Link totop-link

  1. Affected≤ 1.7.1
  2. PatchedNo fix yet

No patched version available.

You are affected if you run ≤ 1.7.1. No fixed version has been released.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under ToTop Link.
  • No admin access? Run a passive check of your site. It reads public files only.
  • No account is needed to exploit this. Treat any exposed site on an affected version as at risk.

What to do

  1. No known patch available. Please review the vulnerability's details in depth and employ mitigations based on your organization's risk tolerance. It may be best to uninstall the affected software and find a replacement.
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch ToTop Link to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Muhammed Kara.

The ToTop Link WordPress plugin through 1.7.1 passes base64 encoded user input to the unserialize() PHP function, which could lead to PHP Object injection if a plugin installed on the blog has a suitable gadget chain.

Exploits & references

Proof-of-concept & detection

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

Advisories & patches

Same weakness (PHP Object Injection)

All PHP Object Injection
Other PHP Object Injection vulnerabilities
SeverityVulnerabilityCVEPublished
High7.2Unauthenticated Stored Cross-Site Scripting via Comment User-Agent HeaderCVE-2026-120688
Critical9.8Unauthenticated Arbitrary File Upload via File Upload via Public Form SubmissionCVE-2026-125055
Critical9.8Unauthenticated PHP Object Injection to Remote Code Execution via 'form' ParameterCVE-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 critical, CVSS 9.0

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. Copyright 2012-2026 Defiant Inc. Licensed under the CC BY-SA 4.0.
CVE® identifiers
Copyright 1999-2026 The MITRE Corporation. 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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