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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-27369

HIGH · 8.1 CVSS v3.1 Published 2026-03-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
90/100
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 BoldThemes Celeste celeste allows Object Injection.This issue affects Celeste: from n/a through <= 1.3.6.

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

PHP Object Injection vulnerability in BoldThemes Celeste theme (versions up to 1.3.6) stemming from unsafe deserialization of untrusted data, allowing remote attackers to inject malicious PHP objects potentially leading to code execution.

MitigationReplace unsafe deserialization (unserialize()) with json_decode() or similar safe methods; implement whitelist validation; update to patched version if available; otherwise disable the theme.

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/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. Locate the Celeste theme installation
    Search for a theme directory named 'celeste' in your web root (commonly in wp-content/themes/celeste/ for WordPress, or themes/celeste/ for other PHP applications)
    Affected if The Celeste theme directory exists on the server
  2. Check the installed theme version
    Open the theme's style.css file (or functions.php) and look for a 'Version:' comment or a $theme_version variable that defines the version number
    Affected if The version is 1.3.6 or lower, or no version is declared (implying an outdated release)
  3. Identify unsafe deserialization calls
    Search all PHP files in the theme directory for the string 'unserialize(' - examine each occurrence to determine if it processes data from external sources (POST, GET, cookies, or database fields)
    Affected if Code contains unserialize() calls that process untrusted user-supplied data
  4. Verify the vulnerable data flow
    Trace each unserialize() call found - determine whether the data being deserialized originates from any user-controlled input (request parameters, HTTP headers, or stored database values)
    Affected if Untrusted user input reaches an unserialize() call without prior validation or sanitization

The environment is affected if the BoldThemes Celeste theme is installed at version 1.3.6 or lower AND the theme contains unserialize() calls that process user-controlled data without validation.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Replace unsafe deserialization (unserialize()) with json_decode() or similar safe methods; implement whitelist validation; update to patched version if available; otherwise disable the theme.

Recommended fix Moderate confidence

Latest available version from BoldThemes (verify fixed version on theme developer's official channels)

  1. 1. Log in to the WordPress admin dashboard
  2. 2. Navigate to Appearance > Themes
  3. 3. Locate the BoldThemes Celeste theme
  4. 4. Check if a newer version is available for download from the official BoldThemes source
  5. 5. If a newer version exists, update the theme to the latest release
  6. 6. If no update is available from the theme developer, consider: a) disabling the Celeste theme and using an alternative, or b) implementing server-side input validation to prevent unserialize() calls on untrusted data
  7. 7. After updating, verify the site functionality remains intact
  8. 8. Monitor for any security advisories from BoldThemes regarding this vulnerability
Caveat Theme updates may include template/structure changes; test thoroughly on staging environment before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2026-27369 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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