CVE-2020-28020

Name: CVE-2020-28020
Creator: NVD / NIST
Published: 2021-05-06T13:15:09.613+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 7.80%

Last modified Jun 17, 2026

CVE-2020-28020 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.. EPSS estimates a 7.80% chance of exploitation in the next 30 days.

Description

Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

7.80%

93.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-190

Affected Software

Vendor	Product	Versions
Exim	Exim	>= 4.00, < 4.92

References

http://www.openwall.com/lists/oss-security/2021/07/25/1Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/08/03/1Mailing List, Third Party Advisory
https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28020-HSIZE.txtPatch, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/07/25/1Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/08/03/1Mailing List, Third Party Advisory
https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28020-HSIZE.txtPatch, Third Party Advisory

Timeline

Published: May 6, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-28020?

How severe is CVE-2020-28020?

CVE-2020-28020 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 7.80% probability of exploitation in the next 30 days.

How do I fix CVE-2020-28020?

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-2020-28020?

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

Scan your code now

Source: NVD / NIST