What is CVE-2021-4118?

CVE-2021-4118 is a high-severity vulnerability in Lightningai Pytorch Lightning, classified under Deserialization of Untrusted Data. CVSS score: 7.8/10. Published 2021-12-23.

How severe is CVE-2021-4118?

High severity. CVSS v3 base score is 7.8 out of 10.

Deserialization in Lightningai Pytorch Lightning

CVE-2021-4118

pytorch-lightning is vulnerable to Deserialization of Untrusted Data

Vulnerability class: Insecure Deserialization

Published 2021-12-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.010 (60.7th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Lightningai Pytorch Lightning
Pytorchlightning Pytorchlightning/pytorch-Lightning — versions unspecified

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

huntr.dev/bounties/31832f0c-e5bb-4552-a12c-542f81f111e6 (Exploit, Patch, Third Party Advisory, Issue Tracking)
github.com/pytorchlightning/pytorch-lightning/commit/62f1e82e032eb16565e676d39e… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-4118?: CVE-2021-4118 is a high-severity vulnerability in Lightningai Pytorch Lightning, classified under Deserialization of Untrusted Data. CVSS score: 7.8/10. Published 2021-12-23.
How severe is CVE-2021-4118?: High severity. CVSS v3 base score is 7.8 out of 10.