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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2025-58998

CRITICAL · 9.8 CVSS v3.1 Published 2025-11-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Deserialization of Untrusted Data vulnerability in Cristián Lávaque s2Member s2member allows Object Injection.This issue affects s2Member: from n/a through <= 250701.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A deserialization vulnerability in s2Member plugin versions up to 250701 allows attackers to inject malicious PHP objects by passing untrusted serialized data, potentially leading to remote code execution through PHP object injection attacks.

MitigationUpdate s2Member to the latest patched version once released; if no patch is available, disable the plugin and review server logs for exploitation attempts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify s2Member installation and version
    Locate the s2Member plugin folder in wp-content/plugins/ and check the main plugin file (usually s2member.php or class-s2-member.php) for the version constant or header comment. Alternatively, query the WordPress database: SELECT option_value FROM wp_options WHERE option_name = 'plugin_version' AND option_name LIKE '%s2member%';
    Affected if The installed version falls within the vulnerable version range (compare your version to the affected releases)
  2. Locate deserialization entry points
    Search plugin source code for unserialize() calls: grep -r "unserialize" /path/to/wp-content/plugins/s2member/ or review s2Member files that handle user input (particularly AJAX handlers, REST endpoints, or files in the /includes/ directory that process request data)
    Affected if The plugin contains unserialize() calls processing $_GET, $_POST, or $_REQUEST parameters without prior sanitization
  3. Verify endpoint accessibility
    Check WordPress permissions settings and s2Member configuration for which user roles can access the identified deserialization endpoints. Review .htaccess or access control settings in s2Member options panel under: s2Member -> API / Options -> API Permissions
    Affected if Endpoints accepting serialized data are accessible to unauthenticated or low-privileged users (anyone other than administrators)
  4. Inspect incoming request handling
    Review the specific file handling the deserialization: examine the $_REQUEST, $_GET, or $_POST variable being passed to unserialize(), typically found in AJAX callbacks or gateway response handlers. Check if the input source is user-controlled without validation.
    Affected if User-supplied input flows directly into unserialize() without sanitization or integrity checks (like hash validation)
  5. Review application logs for exploitation attempts
    Examine Apache/nginx error logs and WordPress debug logs for PHP warnings related to deserialization, or look for unusual object instantiation patterns: grep -i "unserialize" /var/log/apache2/error.log and check access logs for unusual query patterns to s2Member endpoints
    Affected if Recent logs show failed or successful deserialization attempts with serialized payloads (often containing O:\d+ or C:\d+ patterns)

Your environment is affected if s2Member is installed with a vulnerable version containing unserialize() calls that process user-controlled input, and those endpoints are accessible to attackers.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update s2Member to the latest patched version once released; if no patch is available, disable the plugin and review server logs for exploitation attempts.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-58998 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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