CVE-2026-1839Public exploit

Code execution via unsafe checkpoint deserialization

Published Apr 7, 2026 · Updated Apr 7, 2026

Unsafe deserialization in Hugging Face Transformers before 5.0.0rc3 allows attackers to execute code through a malicious checkpoint. Trainer._load_rng_state passes rng_state.pth to torch.load without weights_only=True, permitting pickle-controlled objects to execute during restoration. Exploitation requires the checkpoint to be loaded with PyTorch before 2.6, where the surrounding safe_globals context does not constrain deserialization.

CVSS severity7.8
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Unsafe deserialization in Hugging Face Transformers before 5.0.0rc3 allows attackers to execute code through a malicious checkpoint. Trainer._load_rng_state passes rng_state.pth to torch.load without weights_only=True, permitting pickle-controlled objects to execute during restoration. Exploitation requires the checkpoint to be loaded with PyTorch before 2.6, where the surrounding safe_globals context does not constrain deserialization.

The record

CVE
CVE-2026-1839
Published
Apr 7, 2026
Updated
Apr 7, 2026
Vendor
Hugging Face
Product
Transformers
Classifications
CWE-502, T1204.002, T1059.006
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <v5.0.0rc3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Hugging Face · Transformersversion=unspecified <v5.0.0rc3

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.5GitHubCVSS:3.0/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1204.002User Execution: Malicious File
T1059.006Command and Scripting Interpreter: Python

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo