---
id: CVE-2026-31253
aliases:
  - GHSA-7g5w-pq96-8c5w
  - PYSEC-2026-2477
title: >-
  flash-attention contains an insecure deserialization vulnerability in its
  checkpoint loading mechanism
summary: >-
  flash-attention contains an insecure deserialization vulnerability in its
  checkpoint loading mechanism
severity: high
cvss: 7.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L'
vendor: flash-attn
product: flash-attn
ecosystem: pip
affected:
  - flash-attn <= 2.8.3
published: '2026-05-11'
updated: '2026-07-13'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-7g5w-pq96-8c5w'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-31253'
  - url: 'https://github.com/Dao-AILab/flash-attention'
  - url: 'https://www.notion.so/CVE-2026-31253-35d1e1393188813f9e77e2038104bc49'
tags:
  - osv
  - pip
epss: 0.0037
epssPercentile: 0.28089
ingestedAt: '2026-07-13T18:57:54.333Z'
---

## Overview

The flash-attention training framework thru commit e724e2588cbe754beb97cf7c011b5e7e34119e62 (2025-13-04) contains an insecure deserialization vulnerability (CWE-502) in its checkpoint loading mechanism. The load_checkpoint() function in checkpoint.py and the checkpoint loading code in eval.py use torch.load() without enabling the security-restrictive weights_only=True parameter. This allows the deserialization of arbitrary Python objects via the pickle module. An attacker can exploit this by providing a maliciously crafted checkpoint file. When a victim loads this checkpoint during model warmstarting or evaluation, arbitrary code is executed on the victim's system.

## Affected packages

- `flash-attn <= 2.8.3`

## Remediation

Refer to the advisory for the patched release.