CVE-2021-4070

Name: CVE-2021-4070
Creator: NVD / NIST
Published: 2022-02-23T20:15:09.167+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.1/10EPSS 0.85%

Last modified Jun 17, 2026

CVE-2021-4070 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. Off-by-one Error in GitHub repository v2fly/v2ray-core prior to 4.44.0.. EPSS estimates a 0.85% chance of exploitation in the next 30 days.

Description

Off-by-one Error in GitHub repository v2fly/v2ray-core prior to 4.44.0.

Metrics

CVSS 3.1

9.1/10

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

EPSS Probability

0.85%

53.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
V2fly	V2ray-Core	< 4.44.0

References

https://github.com/v2fly/v2ray-core/commit/c1af2bfd7aa59a4482aa7f6ec4b9208c1d350b5cPatch, Third Party Advisory
https://huntr.dev/bounties/8da19456-4d89-41ef-9781-a41efd6a1877Exploit, Patch, Third Party Advisory
https://github.com/v2fly/v2ray-core/commit/c1af2bfd7aa59a4482aa7f6ec4b9208c1d350b5cPatch, Third Party Advisory
https://huntr.dev/bounties/8da19456-4d89-41ef-9781-a41efd6a1877Exploit, Patch, Third Party Advisory

Timeline

Published: Feb 23, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4070?

Off-by-one Error in GitHub repository v2fly/v2ray-core prior to 4.44.0.

How severe is CVE-2021-4070?

CVE-2021-4070 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.85% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4070?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-4070?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST