CVE-2026-31253Network attack vector

Code execution via unrestricted checkpoint deserialization

Published May 11, 2026 · Updated May 11, 2026

Insecure deserialization in flash-attention allows attackers to execute code by supplying a malicious checkpoint file for loading. The load_checkpoint() function in checkpoint.py and checkpoint loading code in eval.py call torch.load() without weights_only=True, allowing pickle to restore attacker-controlled Python objects. Execution occurs only when the crafted checkpoint is loaded for model warmstarting or evaluation and inherits the training process's privileges.

CVSS severity7.3
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure deserialization in flash-attention allows attackers to execute code by supplying a malicious checkpoint file for loading. The load_checkpoint() function in checkpoint.py and checkpoint loading code in eval.py call torch.load() without weights_only=True, allowing pickle to restore attacker-controlled Python objects. Execution occurs only when the crafted checkpoint is loaded for model warmstarting or evaluation and inherits the training process's privileges.

The record

CVE
CVE-2026-31253
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-502, CWE-94, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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.

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No observations available

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

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
CWE-94Improper Control of Generation of Code ('Code Injection')
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

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Your stack

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