Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-3071

HIGH · 8.4 CVSS v3.1 Published 2026-02-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
89/100
Remediation priority · High
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 in the LanguageModel class of Flair from versions 0.4.1 to latest are vulnerable to arbitrary code execution when loading a malicious model.

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

The LanguageModel class in Flair versions 0.4.1 through latest contains an insecure deserialization vulnerability. When loading a model from an untrusted source, the vulnerable code deserializes data without proper validation, allowing an attacker to execute arbitrary code by supplying a specially crafted malicious model file.

MitigationDo not load Flair models from untrusted or unverified sources. Wait for and apply the official patch when released, which will likely replace the unsafe deserialization mechanism with a safer alternative.

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
Local
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/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. Confirm Flair is installed
    Run 'pip show flair' or check your Python environment for the flair package
    Affected if Flair is not installed, you are not affected
  2. Determine installed Flair version
    Run 'pip show flair' and note the Version field, or import flair and print(flair.__version__)
    Affected if Version is 0.4.1 or higher (any version from 0.4.1 through the latest release is affected)
  3. Identify code that loads Flair LanguageModel
    Search your codebase for imports of 'flair.nn' and usage of 'LanguageModel' class, particularly any load_from_file or similar loading methods
    Affected if Code loads models using LanguageModel class from external or untrusted sources
  4. Check source of loaded model files
    Review all model loading calls and identify whether models are loaded from local trusted files, verifiedpip repositories, or untrusted/network sources
    Affected if Models are loaded from untrusted, unverified, or network sources (this is the attack vector)
  5. Audit model file sources in your environment
    Locate any model files in your project or environment and verify their origin and integrity checksums if possible
    Affected if You have model files of unknown or untrusted origin that could be maliciously crafted

You are affected if Flair version 0.4.1 or higher is installed AND your code loads LanguageModel models from untrusted or unverified external sources.

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

Do not load Flair models from untrusted or unverified sources. Wait for and apply the official patch when released, which will likely replace the unsafe deserialization mechanism with a safer alternative.

Have this fixed Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA6.0 h
42.0 hours of engineering $7,360
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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-2026-3071 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
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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