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Vulnerability details: VCID-dpzd-6sun-a7av
Vulnerability ID VCID-dpzd-6sun-a7av
Aliases CVE-2026-31221
GHSA-75m9-98v2-hjpm
Summary PyTorch-Lightning versions 2.6.0 and earlier contain an insecure deserialization vulnerability (CWE-502) in the checkpoint loading mechanism. The LightningModule.load_from_checkpoint() method, which is commonly used to load saved model states, internally calls torch.load() without setting the security-restrictive weights_only=True parameter. This default behavior allows the deserialization of arbitrary Python objects via the Pickle module. A remote attacker can exploit this by providing a maliciously crafted checkpoint file, leading to arbitrary code execution on the victim's system when the file is loaded.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-502 Deserialization of Untrusted Data
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
epss 0.00191 https://api.first.org/data/v1/epss?cve=CVE-2026-31221
cvssv3.1_qr HIGH https://github.com/advisories/GHSA-75m9-98v2-hjpm
cvssv3.1 7.8 https://github.com/Lightning-AI/pytorch-lightning
cvssv3.1 8.8 https://github.com/Lightning-AI/pytorch-lightning
generic_textual HIGH https://github.com/Lightning-AI/pytorch-lightning
ssvc Track https://github.com/Lightning-AI/pytorch-lightning
cvssv3.1 7.8 https://nvd.nist.gov/vuln/detail/CVE-2026-31221
generic_textual HIGH https://nvd.nist.gov/vuln/detail/CVE-2026-31221
cvssv3.1 7.8 https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
cvssv3.1 8.8 https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
generic_textual HIGH https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
ssvc Track https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2026-31221
https://nvd.nist.gov/vuln/detail/CVE-2026-31221
CVE-2026-31221-35d1e1393188815f8db7c4fd08076639 https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
GHSA-75m9-98v2-hjpm https://github.com/advisories/GHSA-75m9-98v2-hjpm
pytorch-lightning https://github.com/Lightning-AI/pytorch-lightning
No exploits are available.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://github.com/Lightning-AI/pytorch-lightning
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://github.com/Lightning-AI/pytorch-lightning
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

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Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-05-15T18:02:25Z/ Found at https://github.com/Lightning-AI/pytorch-lightning
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2026-31221
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

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physical

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Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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unchanged

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Found at https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

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required

unchanged

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Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-05-15T18:02:25Z/ Found at https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639
Exploit Prediction Scoring System (EPSS)
Percentile 0.40883
EPSS Score 0.00191
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T16:44:51.239460+00:00 Vulnrichment Import https://github.com/cisagov/vulnrichment/blob/develop/2026/31xxx/CVE-2026-31221.json 38.6.0