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CVE-2026-1839: Huggingface Transformers Deserialization of Untrusted Data (CVSS 7.8)

CVE-2026-1839 is a high severity deserialization of untrusted data in Huggingface Transformers with a CVSS score of 7.8. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Last updated: Jun 17, 2026

Quick answer

Direct answer

CVE-2026-1839 is a high severity deserialization of untrusted data in Huggingface Transformers with a CVSS score of 7.8. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Risk scores

CVSS base score
7.8HIGH
EPSS probability
0.38%
Higher than 30 percent of all CVEs
CISA KEV
Not listed
CVSS metricWhat it means
Attack vector (AV:L)Local access needed
Attack complexity (AC:L)Low complexity
Privileges required (PR:N)No privileges required
User interaction (UI:R)A user must take an action
Scope (S:U)Scope unchanged
Confidentiality (C:H)High confidentiality impact
Integrity (I:H)High integrity impact
Availability (A:H)High availability impact

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

About Huggingface Transformers

CVE-2026-1839 affects Huggingface Transformers, a product from Huggingface. Before acting, confirm where Huggingface Transformers runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: A vulnerability in the HuggingFace Transformers library, specifically in the `Trainer` class, allows for arbitrary code execution. The `_load_rng_state()` method in `src/transformers/trainer.py` at line 3059 calls `torch.load()` without the `weights_only=True` parameter. This issue affects all versions of the library supporting `torch>=2.2` when used with PyTorch versions below 2.6, as the `safe_globals()` context manager provides no protection in these versions. An attacker can exploit this vulnerability by supplying a malicious checkpoint file, such as `rng_state.pth`, which can execute arbitrary code when loaded. The issue is resolved in version v5.0.0rc3.

The weakness class is Deserialization of Untrusted Data. The application rebuilds objects from attacker controlled data, which can run code.

Based on its CVSS vector, the flaw needs local or adjacent access, needs no login, and relies on a user taking an action. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Affected versions and timeline

FieldDetail
ProductHuggingface Transformers
Affected versionsTransformers before 5.0.0; Transformers 5.0.0
PublishedApr 7, 2026
Last modifiedJun 17, 2026
Added to CISA KEVNot listed
Assigning CNAsecurity@huntr.dev

How to detect it

  • Inventory every instance of Huggingface Transformers and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Huggingface Transformers named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Huggingface Transformers to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeRank using EPSS and CVSS together with asset exposure and business impact.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-1839 is a high severity deserialization of untrusted data in Huggingface Transformers with a CVSS score of 7.8. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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