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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-25359

HIGH · 8.8 CVSS v3.1 Published 2026-03-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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 rascals Pendulum pendulum allows Object Injection.This issue affects Pendulum: from n/a through < 3.1.5.

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 · high confidence

This is a deserialization of untrusted data vulnerability (Object Injection) in the Pendulum Python datetime library. The library appears to be using Python's pickle or similar deserialization mechanism on untrusted data, allowing attackers to inject malicious serialized objects that could lead to remote code execution.

MitigationUpgrade Pendulum to version 3.1.5 or later to obtain the patched version that properly validates or sanitizes deserialized data. If immediate upgrade is not possible, avoid passing untrusted data to pendulum's deserialization functions.

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

CVSS:3.1/AV:N/AC:L/PR:L/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. Check installed Pendulum version
    Run 'pip show pendulum' or 'python -c "import pendulum; print(pendulum.__version__)"' to retrieve the installed version number
    Affected if The version is lower than 3.1.5 (e.g., 3.1.4, 3.0.0, 2.x, etc.)
  2. Identify deserialization usage in application code
    Search source files for pickle.load(), pickle.loads(), yaml.load(), or similar deserialization functions used with external input
    Affected if The application deserializes data from user input, HTTP request bodies, files from untrusted sources, or network sources
  3. Check if pickle is used with untrusted data
    Grep for 'pickle.load' and 'pickle.loads' calls, then review whether the data source is validated or comes from untrusted origins
    Affected if Pickle deserialization is performed on data that originates from untrusted or external sources
  4. Inspect YAML deserialization if used
    Search for 'yaml.load' with Loader=yaml.UnsafeLoader or missing safe loader specification
    Affected if YAML is loaded with unsafe loaders on data from untrusted sources
  5. Review data input handling for unsafe deserialization
    Examine API endpoints, file upload handlers, message queue consumers, or data import features that accept serialized data
    Affected if The application accepts serialized data (pickle, YAML, etc.) from external sources without validation

You are affected if Pendulum version is below 3.1.5 AND your application deserializes data from untrusted sources using pickle or similar unsafe deserialization methods.

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

Upgrade Pendulum to version 3.1.5 or later to obtain the patched version that properly validates or sanitizes deserialized data. If immediate upgrade is not possible, avoid passing untrusted data to pendulum's deserialization functions.

Recommended fix Moderate confidence

pendulum >= 3.1.5

  1. Upgrade the pendulum Python package to version 3.1.5 or later using pip: pip install pendulum>=3.1.5
  2. Verify the installed version: pip show pendulum
  3. Run application tests to ensure compatibility after the upgrade

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

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,100
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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-2026-25359 in production — separate from our analysis above.

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What this is

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